diff --git a/InvenTree/build/serializers.py b/InvenTree/build/serializers.py
index a18f58fb76..29257341b2 100644
--- a/InvenTree/build/serializers.py
+++ b/InvenTree/build/serializers.py
@@ -422,7 +422,7 @@ class BuildAllocationSerializer(serializers.Serializer):
         Validation
         """
         
-        super().validate(data)
+        data = super().validate(data)
 
         items = data.get('items', [])
 
diff --git a/InvenTree/order/api.py b/InvenTree/order/api.py
index 954295ef8e..037224a855 100644
--- a/InvenTree/order/api.py
+++ b/InvenTree/order/api.py
@@ -13,25 +13,17 @@ from rest_framework import generics
 from rest_framework import filters, status
 from rest_framework.response import Response
 
+from company.models import SupplierPart
 
 from InvenTree.filters import InvenTreeOrderingFilter
 from InvenTree.helpers import str2bool
 from InvenTree.api import AttachmentMixin
 from InvenTree.status_codes import PurchaseOrderStatus, SalesOrderStatus
 
+import order.models as models
+import order.serializers as serializers
+
 from part.models import Part
-from company.models import SupplierPart
-
-from .models import PurchaseOrder, PurchaseOrderLineItem
-from .models import PurchaseOrderAttachment
-from .serializers import POSerializer, POLineItemSerializer, POAttachmentSerializer
-
-from .models import SalesOrder, SalesOrderLineItem, SalesOrderShipment, SalesOrderAllocation
-from .models import SalesOrderAttachment
-
-from .serializers import SalesOrderSerializer, SOLineItemSerializer, SOAttachmentSerializer
-from .serializers import SalesOrderShipmentSerializer, SalesOrderAllocationSerializer
-from .serializers import POReceiveSerializer
 
 
 class POList(generics.ListCreateAPIView):
@@ -41,8 +33,8 @@ class POList(generics.ListCreateAPIView):
     - POST: Create a new PurchaseOrder object
     """
 
-    queryset = PurchaseOrder.objects.all()
-    serializer_class = POSerializer
+    queryset = models.PurchaseOrder.objects.all()
+    serializer_class = serializers.POSerializer
 
     def create(self, request, *args, **kwargs):
         """
@@ -79,7 +71,7 @@ class POList(generics.ListCreateAPIView):
             'lines',
         )
 
-        queryset = POSerializer.annotate_queryset(queryset)
+        queryset = serializers.POSerializer.annotate_queryset(queryset)
 
         return queryset
 
@@ -108,9 +100,9 @@ class POList(generics.ListCreateAPIView):
             overdue = str2bool(overdue)
 
             if overdue:
-                queryset = queryset.filter(PurchaseOrder.OVERDUE_FILTER)
+                queryset = queryset.filter(models.PurchaseOrder.OVERDUE_FILTER)
             else:
-                queryset = queryset.exclude(PurchaseOrder.OVERDUE_FILTER)
+                queryset = queryset.exclude(models.PurchaseOrder.OVERDUE_FILTER)
 
         # Special filtering for 'status' field
         status = params.get('status', None)
@@ -144,7 +136,7 @@ class POList(generics.ListCreateAPIView):
         max_date = params.get('max_date', None)
 
         if min_date is not None and max_date is not None:
-            queryset = PurchaseOrder.filterByDate(queryset, min_date, max_date)
+            queryset = models.PurchaseOrder.filterByDate(queryset, min_date, max_date)
 
         return queryset
 
@@ -184,8 +176,8 @@ class POList(generics.ListCreateAPIView):
 class PODetail(generics.RetrieveUpdateDestroyAPIView):
     """ API endpoint for detail view of a PurchaseOrder object """
 
-    queryset = PurchaseOrder.objects.all()
-    serializer_class = POSerializer
+    queryset = models.PurchaseOrder.objects.all()
+    serializer_class = serializers.POSerializer
 
     def get_serializer(self, *args, **kwargs):
 
@@ -208,7 +200,7 @@ class PODetail(generics.RetrieveUpdateDestroyAPIView):
             'lines',
         )
 
-        queryset = POSerializer.annotate_queryset(queryset)
+        queryset = serializers.POSerializer.annotate_queryset(queryset)
 
         return queryset
 
@@ -226,9 +218,9 @@ class POReceive(generics.CreateAPIView):
     - A global location can also be specified
     """
 
-    queryset = PurchaseOrderLineItem.objects.none()
+    queryset = models.PurchaseOrderLineItem.objects.none()
 
-    serializer_class = POReceiveSerializer
+    serializer_class = serializers.POReceiveSerializer
 
     def get_serializer_context(self):
 
@@ -236,7 +228,7 @@ class POReceive(generics.CreateAPIView):
 
         # Pass the purchase order through to the serializer for validation
         try:
-            context['order'] = PurchaseOrder.objects.get(pk=self.kwargs.get('pk', None))
+            context['order'] = models.PurchaseOrder.objects.get(pk=self.kwargs.get('pk', None))
         except:
             pass
 
@@ -251,7 +243,7 @@ class POLineItemFilter(rest_filters.FilterSet):
     """
 
     class Meta:
-        model = PurchaseOrderLineItem
+        model = models.PurchaseOrderLineItem
         fields = [
             'order',
             'part'
@@ -285,15 +277,15 @@ class POLineItemList(generics.ListCreateAPIView):
     - POST: Create a new PurchaseOrderLineItem object
     """
 
-    queryset = PurchaseOrderLineItem.objects.all()
-    serializer_class = POLineItemSerializer
+    queryset = models.PurchaseOrderLineItem.objects.all()
+    serializer_class = serializers.POLineItemSerializer
     filterset_class = POLineItemFilter
 
     def get_queryset(self, *args, **kwargs):
 
         queryset = super().get_queryset(*args, **kwargs)
 
-        queryset = POLineItemSerializer.annotate_queryset(queryset)
+        queryset = serializers.POLineItemSerializer.annotate_queryset(queryset)
 
         return queryset
 
@@ -350,14 +342,14 @@ class POLineItemDetail(generics.RetrieveUpdateDestroyAPIView):
     Detail API endpoint for PurchaseOrderLineItem object
     """
 
-    queryset = PurchaseOrderLineItem.objects.all()
-    serializer_class = POLineItemSerializer
+    queryset = models.PurchaseOrderLineItem.objects.all()
+    serializer_class = serializers.POLineItemSerializer
 
     def get_queryset(self):
 
         queryset = super().get_queryset()
 
-        queryset = POLineItemSerializer.annotate_queryset(queryset)
+        queryset = serializers.POLineItemSerializer.annotate_queryset(queryset)
 
         return queryset
 
@@ -367,8 +359,8 @@ class SOAttachmentList(generics.ListCreateAPIView, AttachmentMixin):
     API endpoint for listing (and creating) a SalesOrderAttachment (file upload)
     """
 
-    queryset = SalesOrderAttachment.objects.all()
-    serializer_class = SOAttachmentSerializer
+    queryset = models.SalesOrderAttachment.objects.all()
+    serializer_class = serializers.SOAttachmentSerializer
 
     filter_backends = [
         rest_filters.DjangoFilterBackend,
@@ -384,8 +376,8 @@ class SOAttachmentDetail(generics.RetrieveUpdateDestroyAPIView, AttachmentMixin)
     Detail endpoint for SalesOrderAttachment
     """
 
-    queryset = SalesOrderAttachment.objects.all()
-    serializer_class = SOAttachmentSerializer
+    queryset = models.SalesOrderAttachment.objects.all()
+    serializer_class = serializers.SOAttachmentSerializer
 
 
 class SOList(generics.ListCreateAPIView):
@@ -396,8 +388,8 @@ class SOList(generics.ListCreateAPIView):
     - POST: Create a new SalesOrder
     """
 
-    queryset = SalesOrder.objects.all()
-    serializer_class = SalesOrderSerializer
+    queryset = models.SalesOrder.objects.all()
+    serializer_class = serializers.SalesOrderSerializer
 
     def create(self, request, *args, **kwargs):
         """
@@ -434,7 +426,7 @@ class SOList(generics.ListCreateAPIView):
             'lines'
         )
 
-        queryset = SalesOrderSerializer.annotate_queryset(queryset)
+        queryset = serializers.SalesOrderSerializer.annotate_queryset(queryset)
 
         return queryset
 
@@ -454,9 +446,9 @@ class SOList(generics.ListCreateAPIView):
             outstanding = str2bool(outstanding)
 
             if outstanding:
-                queryset = queryset.filter(status__in=SalesOrderStatus.OPEN)
+                queryset = queryset.filter(status__in=models.SalesOrderStatus.OPEN)
             else:
-                queryset = queryset.exclude(status__in=SalesOrderStatus.OPEN)
+                queryset = queryset.exclude(status__in=models.SalesOrderStatus.OPEN)
 
         # Filter by 'overdue' status
         overdue = params.get('overdue', None)
@@ -465,9 +457,9 @@ class SOList(generics.ListCreateAPIView):
             overdue = str2bool(overdue)
 
             if overdue:
-                queryset = queryset.filter(SalesOrder.OVERDUE_FILTER)
+                queryset = queryset.filter(models.SalesOrder.OVERDUE_FILTER)
             else:
-                queryset = queryset.exclude(SalesOrder.OVERDUE_FILTER)
+                queryset = queryset.exclude(models.SalesOrder.OVERDUE_FILTER)
 
         status = params.get('status', None)
 
@@ -490,7 +482,7 @@ class SOList(generics.ListCreateAPIView):
         max_date = params.get('max_date', None)
 
         if min_date is not None and max_date is not None:
-            queryset = SalesOrder.filterByDate(queryset, min_date, max_date)
+            queryset = models.SalesOrder.filterByDate(queryset, min_date, max_date)
 
         return queryset
 
@@ -534,8 +526,8 @@ class SODetail(generics.RetrieveUpdateDestroyAPIView):
     API endpoint for detail view of a SalesOrder object.
     """
 
-    queryset = SalesOrder.objects.all()
-    serializer_class = SalesOrderSerializer
+    queryset = models.SalesOrder.objects.all()
+    serializer_class = serializers.SalesOrderSerializer
 
     def get_serializer(self, *args, **kwargs):
 
@@ -554,7 +546,7 @@ class SODetail(generics.RetrieveUpdateDestroyAPIView):
 
         queryset = queryset.prefetch_related('customer', 'lines')
 
-        queryset = SalesOrderSerializer.annotate_queryset(queryset)
+        queryset = serializers.SalesOrderSerializer.annotate_queryset(queryset)
 
         return queryset
 
@@ -564,8 +556,8 @@ class SOLineItemList(generics.ListCreateAPIView):
     API endpoint for accessing a list of SalesOrderLineItem objects.
     """
 
-    queryset = SalesOrderLineItem.objects.all()
-    serializer_class = SOLineItemSerializer
+    queryset = models.SalesOrderLineItem.objects.all()
+    serializer_class = serializers.SOLineItemSerializer
 
     def get_serializer(self, *args, **kwargs):
 
@@ -624,8 +616,34 @@ class SOLineItemList(generics.ListCreateAPIView):
 class SOLineItemDetail(generics.RetrieveUpdateDestroyAPIView):
     """ API endpoint for detail view of a SalesOrderLineItem object """
 
-    queryset = SalesOrderLineItem.objects.all()
-    serializer_class = SOLineItemSerializer
+    queryset = models.SalesOrderLineItem.objects.all()
+    serializer_class = serializers.SOLineItemSerializer
+
+
+class SalesOrderAllocate(generics.CreateAPIView):
+    """
+    API endpoint to allocate stock items against a SalesOrder
+
+    - The SalesOrder is specified in the URL
+    - See the SOShipmentAllocationSerializer class
+    """
+
+    queryset = models.SalesOrder.objects.none()
+    serializer_class = serializers.SOShipmentAllocationSerializer
+
+    def get_serializer_context(self):
+
+        ctx = super().get_serializer_context()
+
+        # Pass through the SalesOrder object to the serializer
+        try:
+            ctx['order'] = models.SalesOrder.objects.get(pk=self.kwargs.get('pk', None))
+        except:
+            pass
+
+        ctx['request'] = self.request
+
+        return ctx
 
 
 class SOAllocationDetail(generics.RetrieveUpdateDestroyAPIView):
@@ -633,17 +651,17 @@ class SOAllocationDetail(generics.RetrieveUpdateDestroyAPIView):
     API endpoint for detali view of a SalesOrderAllocation object
     """
 
-    queryset = SalesOrderAllocation.objects.all()
-    serializer_class = SalesOrderAllocationSerializer
+    queryset = models.SalesOrderAllocation.objects.all()
+    serializer_class = serializers.SalesOrderAllocationSerializer
 
 
-class SOAllocationList(generics.ListCreateAPIView):
+class SOAllocationList(generics.ListAPIView):
     """
     API endpoint for listing SalesOrderAllocation objects
     """
 
-    queryset = SalesOrderAllocation.objects.all()
-    serializer_class = SalesOrderAllocationSerializer
+    queryset = models.SalesOrderAllocation.objects.all()
+    serializer_class = serializers.SalesOrderAllocationSerializer
 
     def get_serializer(self, *args, **kwargs):
 
@@ -720,7 +738,7 @@ class SOShipmentFilter(rest_filters.FilterSet):
         return queryset
 
     class Meta:
-        model = SalesOrderShipment
+        model = models.SalesOrderShipment
         fields = [
             'order',
         ]
@@ -731,8 +749,8 @@ class SOShipmentList(generics.ListCreateAPIView):
     API list endpoint for SalesOrderShipment model
     """
 
-    queryset = SalesOrderShipment.objects.all()
-    serializer_class = SalesOrderShipmentSerializer
+    queryset = models.SalesOrderShipment.objects.all()
+    serializer_class = serializers.SalesOrderShipmentSerializer
     filterset_class = SOShipmentFilter
 
     filter_backends = [
@@ -745,8 +763,8 @@ class SOShipmentDetail(generics.RetrieveUpdateAPIView):
     API detail endpooint for SalesOrderShipment model
     """
 
-    queryset = SalesOrderShipment.objects.all()
-    serializer_class = SalesOrderShipmentSerializer
+    queryset = models.SalesOrderShipment.objects.all()
+    serializer_class = serializers.SalesOrderShipmentSerializer
 
 
 class POAttachmentList(generics.ListCreateAPIView, AttachmentMixin):
@@ -754,8 +772,8 @@ class POAttachmentList(generics.ListCreateAPIView, AttachmentMixin):
     API endpoint for listing (and creating) a PurchaseOrderAttachment (file upload)
     """
 
-    queryset = PurchaseOrderAttachment.objects.all()
-    serializer_class = POAttachmentSerializer
+    queryset = models.PurchaseOrderAttachment.objects.all()
+    serializer_class = serializers.POAttachmentSerializer
 
     filter_backends = [
         rest_filters.DjangoFilterBackend,
@@ -771,8 +789,8 @@ class POAttachmentDetail(generics.RetrieveUpdateDestroyAPIView, AttachmentMixin)
     Detail endpoint for a PurchaseOrderAttachment
     """
 
-    queryset = PurchaseOrderAttachment.objects.all()
-    serializer_class = POAttachmentSerializer
+    queryset = models.PurchaseOrderAttachment.objects.all()
+    serializer_class = serializers.POAttachmentSerializer
 
 
 order_api_urls = [
@@ -816,7 +834,13 @@ order_api_urls = [
             url(r'^.*$', SOShipmentList.as_view(), name='api-so-shipment-list'),
         ])),
 
-        url(r'^(?P<pk>\d+)/$', SODetail.as_view(), name='api-so-detail'),
+        # Sales order detail view
+        url(r'^(?P<pk>\d+)/', include([
+            url(r'^allocate/', SalesOrderAllocate.as_view(), name='api-so-allocate'),
+            url(r'^.*$', SODetail.as_view(), name='api-so-detail'),
+        ])),
+
+        # Sales order list view
         url(r'^.*$', SOList.as_view(), name='api-so-list'),
     ])),
 
diff --git a/InvenTree/order/models.py b/InvenTree/order/models.py
index b0b0d82221..05eabe3788 100644
--- a/InvenTree/order/models.py
+++ b/InvenTree/order/models.py
@@ -567,6 +567,16 @@ class SalesOrder(Order):
     def is_pending(self):
         return self.status == SalesOrderStatus.PENDING
 
+    @property
+    def stock_allocations(self):
+        """
+        Return a queryset containing all allocations for this order
+        """
+
+        return SalesOrderAllocation.objects.filter(
+            line__in=[line.pk for line in self.lines.all()]
+        )
+
     def is_fully_allocated(self):
         """ Return True if all line items are fully allocated """
 
@@ -910,6 +920,10 @@ class SalesOrderShipment(models.Model):
         notes: Custom notes field for this shipment
     """
 
+    @staticmethod
+    def get_api_url():
+        return reverse('api-so-shipment-list')
+
     order = models.ForeignKey(
         SalesOrder,
         on_delete=models.CASCADE,
@@ -1014,10 +1028,9 @@ class SalesOrderAllocation(models.Model):
         if self.item.serial and not self.quantity == 1:
             errors['quantity'] = _('Quantity must be 1 for serialized stock item')
 
-
-
-        # TODO: Ensure that the "shipment" points to the same "order"!
-
+        if self.line.order != self.shipment.order:
+            errors['line'] = _('Sales order does not match shipment')
+            errors['shipment'] = _('Shipment does not match sales order')
 
         if len(errors) > 0:
             raise ValidationError(errors)
@@ -1026,7 +1039,8 @@ class SalesOrderAllocation(models.Model):
         SalesOrderLineItem,
         on_delete=models.CASCADE,
         verbose_name=_('Line'),
-        related_name='allocations')
+        related_name='allocations'
+    )
 
     shipment = models.ForeignKey(
         SalesOrderShipment,
diff --git a/InvenTree/order/serializers.py b/InvenTree/order/serializers.py
index 70bef86ae4..34032d758b 100644
--- a/InvenTree/order/serializers.py
+++ b/InvenTree/order/serializers.py
@@ -17,30 +17,29 @@ from rest_framework.serializers import ValidationError
 
 from sql_util.utils import SubqueryCount
 
+from common.settings import currency_code_mappings
+
+from company.serializers import CompanyBriefSerializer, SupplierPartSerializer
+
+from InvenTree.helpers import normalize
 from InvenTree.serializers import InvenTreeModelSerializer
 from InvenTree.serializers import InvenTreeAttachmentSerializer
 from InvenTree.serializers import InvenTreeMoneySerializer
 from InvenTree.serializers import InvenTreeAttachmentSerializerField
-
 from InvenTree.status_codes import StockStatus
 
-from company.serializers import CompanyBriefSerializer, SupplierPartSerializer
+import order.models
 
 from part.serializers import PartBriefSerializer
 
 import stock.models
-from stock.serializers import LocationBriefSerializer, StockItemSerializer, LocationSerializer
-
-from .models import PurchaseOrder, PurchaseOrderLineItem
-from .models import PurchaseOrderAttachment, SalesOrderAttachment
-from .models import SalesOrder, SalesOrderLineItem
-from .models import SalesOrderShipment, SalesOrderAllocation
-
-from common.settings import currency_code_mappings
+import stock.serializers
 
 
 class POSerializer(InvenTreeModelSerializer):
-    """ Serializer for a PurchaseOrder object """
+    """
+    Serializer for a PurchaseOrder object
+    """
 
     def __init__(self, *args, **kwargs):
 
@@ -67,7 +66,7 @@ class POSerializer(InvenTreeModelSerializer):
         queryset = queryset.annotate(
             overdue=Case(
                 When(
-                    PurchaseOrder.OVERDUE_FILTER, then=Value(True, output_field=BooleanField()),
+                    order.models.PurchaseOrder.OVERDUE_FILTER, then=Value(True, output_field=BooleanField()),
                 ),
                 default=Value(False, output_field=BooleanField())
             )
@@ -86,7 +85,7 @@ class POSerializer(InvenTreeModelSerializer):
     reference = serializers.CharField(required=True)
 
     class Meta:
-        model = PurchaseOrder
+        model = order.models.PurchaseOrder
 
         fields = [
             'pk',
@@ -160,7 +159,7 @@ class POLineItemSerializer(InvenTreeModelSerializer):
 
     purchase_price_string = serializers.CharField(source='purchase_price', read_only=True)
 
-    destination_detail = LocationBriefSerializer(source='get_destination', read_only=True)
+    destination_detail = stock.serializers.LocationBriefSerializer(source='get_destination', read_only=True)
 
     purchase_price_currency = serializers.ChoiceField(
         choices=currency_code_mappings(),
@@ -168,7 +167,7 @@ class POLineItemSerializer(InvenTreeModelSerializer):
     )
 
     class Meta:
-        model = PurchaseOrderLineItem
+        model = order.models.PurchaseOrderLineItem
 
         fields = [
             'pk',
@@ -195,7 +194,7 @@ class POLineItemReceiveSerializer(serializers.Serializer):
     """
 
     line_item = serializers.PrimaryKeyRelatedField(
-        queryset=PurchaseOrderLineItem.objects.all(),
+        queryset=order.models.PurchaseOrderLineItem.objects.all(),
         many=False,
         allow_null=False,
         required=True,
@@ -376,7 +375,7 @@ class POAttachmentSerializer(InvenTreeAttachmentSerializer):
     attachment = InvenTreeAttachmentSerializerField(required=True)
 
     class Meta:
-        model = PurchaseOrderAttachment
+        model = order.models.PurchaseOrderAttachment
 
         fields = [
             'pk',
@@ -422,7 +421,7 @@ class SalesOrderSerializer(InvenTreeModelSerializer):
         queryset = queryset.annotate(
             overdue=Case(
                 When(
-                    SalesOrder.OVERDUE_FILTER, then=Value(True, output_field=BooleanField()),
+                    order.models.SalesOrder.OVERDUE_FILTER, then=Value(True, output_field=BooleanField()),
                 ),
                 default=Value(False, output_field=BooleanField())
             )
@@ -441,7 +440,7 @@ class SalesOrderSerializer(InvenTreeModelSerializer):
     reference = serializers.CharField(required=True)
 
     class Meta:
-        model = SalesOrder
+        model = order.models.SalesOrder
 
         fields = [
             'pk',
@@ -484,8 +483,8 @@ class SalesOrderAllocationSerializer(InvenTreeModelSerializer):
     # Extra detail fields
     order_detail = SalesOrderSerializer(source='line.order', many=False, read_only=True)
     part_detail = PartBriefSerializer(source='item.part', many=False, read_only=True)
-    item_detail = StockItemSerializer(source='item', many=False, read_only=True)
-    location_detail = LocationSerializer(source='item.location', many=False, read_only=True)
+    item_detail = stock.serializers.StockItemSerializer(source='item', many=False, read_only=True)
+    location_detail = stock.serializers.LocationSerializer(source='item.location', many=False, read_only=True)
 
     def __init__(self, *args, **kwargs):
 
@@ -509,7 +508,7 @@ class SalesOrderAllocationSerializer(InvenTreeModelSerializer):
             self.fields.pop('location_detail')
 
     class Meta:
-        model = SalesOrderAllocation
+        model = order.models.SalesOrderAllocation
 
         fields = [
             'pk',
@@ -570,7 +569,7 @@ class SOLineItemSerializer(InvenTreeModelSerializer):
     )
 
     class Meta:
-        model = SalesOrderLineItem
+        model = order.models.SalesOrderLineItem
 
         fields = [
             'pk',
@@ -598,7 +597,7 @@ class SalesOrderShipmentSerializer(InvenTreeModelSerializer):
     allocations = SalesOrderAllocationSerializer(many=True, read_only=True, location_detail=True)
 
     class Meta:
-        model = SalesOrderShipment
+        model = order.models.SalesOrderShipment
 
         fields = [
             'pk',
@@ -611,6 +610,160 @@ class SalesOrderShipmentSerializer(InvenTreeModelSerializer):
         ]
 
 
+class SOShipmentAllocationItemSerializer(serializers.Serializer):
+    """
+    A serializer for allocating a single stock-item against a SalesOrder shipment
+    """
+
+    class Meta:
+        fields = [
+            'line_item',
+            'stock_item',
+            'quantity',
+        ]
+
+    line_item = serializers.PrimaryKeyRelatedField(
+        queryset=order.models.SalesOrderLineItem.objects.all(),
+        many=False,
+        allow_null=False,
+        required=True,
+        label=_('Stock Item'),
+    )
+
+    def validate_line_item(self, line_item):
+
+        order = self.context['order']
+
+        # Ensure that the line item points to the correct order
+        if line_item.order != order:
+            raise ValidationError(_("Line item is not associated with this order"))
+
+        return line_item
+
+    stock_item = serializers.PrimaryKeyRelatedField(
+        queryset=stock.models.StockItem.objects.all(),
+        many=False,
+        allow_null=False,
+        required=True,
+        label=_('Stock Item'),
+    )
+
+    quantity = serializers.DecimalField(
+        max_digits=15,
+        decimal_places=5,
+        min_value=0,
+        required=True
+    )
+
+    def validate_quantity(self, quantity):
+
+        if quantity <= 0:
+            raise ValidationError(_("Quantity must be positive"))
+
+        return quantity
+
+    def validate(self, data):
+
+        super().validate(data)
+
+        stock_item = data['stock_item']
+        quantity = data['quantity']
+
+        if stock_item.serialized and quantity != 1:
+            raise ValidationError({
+                'quantity': _("Quantity must be 1 for serialized stock item"),
+            })
+
+        q = normalize(stock_item.unallocated_quantity())
+
+        if quantity > q:
+            raise ValidationError({
+                'quantity': _(f"Available quantity ({q}) exceeded")
+            })
+
+        return data
+
+
+class SOShipmentAllocationSerializer(serializers.Serializer):
+    """
+    DRF serializer for allocation of stock items against a sales order / shipment
+    """
+
+    class Meta:
+        fields = [
+            'items',
+            'shipment',
+        ]
+
+    items = SOShipmentAllocationItemSerializer(many=True)
+
+    shipment = serializers.PrimaryKeyRelatedField(
+        queryset=order.models.SalesOrderShipment.objects.all(),
+        many=False,
+        allow_null=False,
+        required=True,
+        label=_('Shipment'),
+    )
+
+    def validate_shipment(self, shipment):
+        """
+        Run validation against the provided shipment instance
+        """
+
+        order = self.context['order']
+
+        if shipment.shipment_date is not None:
+            raise ValidationError(_("Shipment has already been shipped"))
+
+        if shipment.order != order:
+            raise ValidationError(_("Shipment is not associated with this order"))
+
+        return shipment
+
+    def validate(self, data):
+        """
+        Serializer validation
+        """
+
+        data = super().validate(data)
+
+        # Extract SalesOrder from serializer context
+        # order = self.context['order']
+
+        items = data.get('items', [])
+
+        if len(items) == 0:
+            raise ValidationError(_('Allocation items must be provided'))
+
+        return data
+
+    def save(self):
+        """
+        Perform the allocation of items against this order
+        """
+
+        data = self.validated_data
+
+        items = data['items']
+        shipment = data['shipment']
+
+        with transaction.atomic():
+            for entry in items:
+                
+                # Create a new SalesOrderAllocation
+                order.models.SalesOrderAllocation.objects.create(
+                    line=entry.get('line_item'),
+                    item=entry.get('stock_item'),
+                    quantity=entry.get('quantity'),
+                    shipment=shipment,
+                )
+
+                try:
+                    pass
+                except (ValidationError, DjangoValidationError) as exc:
+                    raise ValidationError(detail=serializers.as_serializer_error(exc))
+
+
 class SOAttachmentSerializer(InvenTreeAttachmentSerializer):
     """
     Serializers for the SalesOrderAttachment model
@@ -619,7 +772,7 @@ class SOAttachmentSerializer(InvenTreeAttachmentSerializer):
     attachment = InvenTreeAttachmentSerializerField(required=True)
 
     class Meta:
-        model = SalesOrderAttachment
+        model = order.models.SalesOrderAttachment
 
         fields = [
             'pk',
diff --git a/InvenTree/order/test_api.py b/InvenTree/order/test_api.py
index 899fa9a6fc..0f29e5bd16 100644
--- a/InvenTree/order/test_api.py
+++ b/InvenTree/order/test_api.py
@@ -11,9 +11,10 @@ from django.urls import reverse
 from InvenTree.api_tester import InvenTreeAPITestCase
 from InvenTree.status_codes import PurchaseOrderStatus
 
+from part.models import Part
 from stock.models import StockItem
 
-from .models import PurchaseOrder, PurchaseOrderLineItem, SalesOrder
+import order.models as models
 
 
 class OrderTest(InvenTreeAPITestCase):
@@ -85,7 +86,7 @@ class PurchaseOrderTest(OrderTest):
         self.filter({'overdue': True}, 0)
         self.filter({'overdue': False}, 7)
 
-        order = PurchaseOrder.objects.get(pk=1)
+        order = models.PurchaseOrder.objects.get(pk=1)
         order.target_date = datetime.now().date() - timedelta(days=10)
         order.save()
 
@@ -118,7 +119,7 @@ class PurchaseOrderTest(OrderTest):
         Test that we can create / edit and delete a PurchaseOrder via the API
         """
 
-        n = PurchaseOrder.objects.count()
+        n = models.PurchaseOrder.objects.count()
 
         url = reverse('api-po-list')
 
@@ -135,7 +136,7 @@ class PurchaseOrderTest(OrderTest):
         )
 
         # And no new PurchaseOrder objects should have been created
-        self.assertEqual(PurchaseOrder.objects.count(), n)
+        self.assertEqual(models.PurchaseOrder.objects.count(), n)
 
         # Ok, now let's give this user the correct permission
         self.assignRole('purchase_order.add')
@@ -152,7 +153,7 @@ class PurchaseOrderTest(OrderTest):
             expected_code=201
         )
 
-        self.assertEqual(PurchaseOrder.objects.count(), n + 1)
+        self.assertEqual(models.PurchaseOrder.objects.count(), n + 1)
 
         pk = response.data['pk']
 
@@ -167,7 +168,7 @@ class PurchaseOrderTest(OrderTest):
             expected_code=400
         )
 
-        self.assertEqual(PurchaseOrder.objects.count(), n + 1)
+        self.assertEqual(models.PurchaseOrder.objects.count(), n + 1)
 
         url = reverse('api-po-detail', kwargs={'pk': pk})
 
@@ -198,7 +199,7 @@ class PurchaseOrderTest(OrderTest):
         response = self.delete(url, expected_code=204)
 
         # Number of PurchaseOrder objects should have decreased
-        self.assertEqual(PurchaseOrder.objects.count(), n)
+        self.assertEqual(models.PurchaseOrder.objects.count(), n)
 
         # And if we try to access the detail view again, it has gone
         response = self.get(url, expected_code=404)
@@ -237,7 +238,7 @@ class PurchaseOrderReceiveTest(OrderTest):
         self.n = StockItem.objects.count()
 
         # Mark the order as "placed" so we can receive line items
-        order = PurchaseOrder.objects.get(pk=1)
+        order = models.PurchaseOrder.objects.get(pk=1)
         order.status = PurchaseOrderStatus.PLACED
         order.save()
 
@@ -409,8 +410,8 @@ class PurchaseOrderReceiveTest(OrderTest):
         Test receipt of valid data
         """
 
-        line_1 = PurchaseOrderLineItem.objects.get(pk=1)
-        line_2 = PurchaseOrderLineItem.objects.get(pk=2)
+        line_1 = models.PurchaseOrderLineItem.objects.get(pk=1)
+        line_2 = models.PurchaseOrderLineItem.objects.get(pk=2)
 
         self.assertEqual(StockItem.objects.filter(supplier_part=line_1.part).count(), 0)
         self.assertEqual(StockItem.objects.filter(supplier_part=line_2.part).count(), 0)
@@ -437,7 +438,7 @@ class PurchaseOrderReceiveTest(OrderTest):
 
         # Before posting "valid" data, we will mark the purchase order as "pending"
         # In this case we do expect an error!
-        order = PurchaseOrder.objects.get(pk=1)
+        order = models.PurchaseOrder.objects.get(pk=1)
         order.status = PurchaseOrderStatus.PENDING
         order.save()
 
@@ -463,8 +464,8 @@ class PurchaseOrderReceiveTest(OrderTest):
         # There should be two newly created stock items
         self.assertEqual(self.n + 2, StockItem.objects.count())
 
-        line_1 = PurchaseOrderLineItem.objects.get(pk=1)
-        line_2 = PurchaseOrderLineItem.objects.get(pk=2)
+        line_1 = models.PurchaseOrderLineItem.objects.get(pk=1)
+        line_2 = models.PurchaseOrderLineItem.objects.get(pk=2)
 
         self.assertEqual(line_1.received, 50)
         self.assertEqual(line_2.received, 250)
@@ -519,7 +520,7 @@ class SalesOrderTest(OrderTest):
         self.filter({'overdue': False}, 5)
 
         for pk in [1, 2]:
-            order = SalesOrder.objects.get(pk=pk)
+            order = models.SalesOrder.objects.get(pk=pk)
             order.target_date = datetime.now().date() - timedelta(days=10)
             order.save()
 
@@ -547,7 +548,7 @@ class SalesOrderTest(OrderTest):
         Test that we can create / edit and delete a SalesOrder via the API
         """
 
-        n = SalesOrder.objects.count()
+        n = models.SalesOrder.objects.count()
 
         url = reverse('api-so-list')
 
@@ -577,7 +578,7 @@ class SalesOrderTest(OrderTest):
         )
 
         # Check that the new order has been created
-        self.assertEqual(SalesOrder.objects.count(), n + 1)
+        self.assertEqual(models.SalesOrder.objects.count(), n + 1)
 
         # Grab the PK for the newly created SalesOrder
         pk = response.data['pk']
@@ -620,7 +621,7 @@ class SalesOrderTest(OrderTest):
         response = self.delete(url, expected_code=204)
 
         # Check that the number of sales orders has decreased
-        self.assertEqual(SalesOrder.objects.count(), n)
+        self.assertEqual(models.SalesOrder.objects.count(), n)
 
         # And the resource should no longer be available
         response = self.get(url, expected_code=404)
@@ -641,3 +642,131 @@ class SalesOrderTest(OrderTest):
             },
             expected_code=201
         )
+
+
+class SalesOrderAllocateTest(OrderTest):
+    """
+    Unit tests for allocating stock items against a SalesOrder
+    """
+
+    def setUp(self):
+        super().setUp()
+
+        self.assignRole('sales_order.add')
+
+        self.url = reverse('api-so-allocate', kwargs={'pk': 1})
+
+        self.order = models.SalesOrder.objects.get(pk=1)
+
+        # Create some line items for this purchase order
+        parts = Part.objects.filter(salable=True)
+
+        for part in parts:
+
+            # Create a new line item
+            models.SalesOrderLineItem.objects.create(
+                order=self.order,
+                part=part,
+                quantity=5,
+            )
+
+            # Ensure we have stock!
+            StockItem.objects.create(
+                part=part,
+                quantity=100,
+            )
+
+        # Create a new shipment against this SalesOrder
+        self.shipment = models.SalesOrderShipment.objects.create(
+            order=self.order,
+        )
+
+    def test_invalid(self):
+        """
+        Test POST with invalid data
+        """
+
+        # No data
+        response = self.post(self.url, {}, expected_code=400)
+
+        self.assertIn('This field is required', str(response.data['items']))
+        self.assertIn('This field is required', str(response.data['shipment']))
+
+        # Test with a single line items
+        line = self.order.lines.first()
+        part = line.part
+
+        # Valid stock_item, but quantity is invalid
+        data = {
+            'items': [{
+                "line_item": line.pk,
+                "stock_item": part.stock_items.last().pk,
+                "quantity": 0,
+            }],
+        }
+
+        response = self.post(self.url, data, expected_code=400)
+
+        self.assertIn('Quantity must be positive', str(response.data['items']))
+
+        # Valid stock item, too much quantity
+        data['items'][0]['quantity'] = 250
+
+        response = self.post(self.url, data, expected_code=400)
+
+        self.assertIn('Available quantity (100) exceeded', str(response.data['items']))
+
+        # Valid stock item, valid quantity
+        data['items'][0]['quantity'] = 50
+
+        # Invalid shipment!
+        data['shipment'] = 9999
+
+        response = self.post(self.url, data, expected_code=400)
+
+        self.assertIn('does not exist', str(response.data['shipment']))
+
+        # Valid shipment, but points to the wrong order
+        shipment = models.SalesOrderShipment.objects.create(
+            order=models.SalesOrder.objects.get(pk=2),
+        )
+
+        data['shipment'] = shipment.pk
+
+        response = self.post(self.url, data, expected_code=400)
+
+        self.assertIn('Shipment is not associated with this order', str(response.data['shipment']))
+
+    def test_allocate(self):
+        """
+        Test the the allocation endpoint acts as expected,
+        when provided with valid data!
+        """
+
+        # First, check that there are no line items allocated against this SalesOrder
+        self.assertEqual(self.order.stock_allocations.count(), 0)
+
+        data = {
+            "items": [],
+            "shipment": self.shipment.pk,
+        }
+
+        for line in self.order.lines.all():
+            stock_item = line.part.stock_items.last()
+
+            # Fully-allocate each line
+            data['items'].append({
+                "line_item": line.pk,
+                "stock_item": stock_item.pk,
+                "quantity": 5
+            })
+
+        self.post(self.url, data, expected_code=201)
+
+        # There should have been 1 stock item allocated against each line item
+        n_lines = self.order.lines.count()
+
+        self.assertEqual(self.order.stock_allocations.count(), n_lines)
+
+        for line in self.order.lines.all():
+            self.assertEqual(line.allocations.count(), 1)
diff --git a/InvenTree/part/fixtures/part.yaml b/InvenTree/part/fixtures/part.yaml
index 3c24690efc..77e808fd7f 100644
--- a/InvenTree/part/fixtures/part.yaml
+++ b/InvenTree/part/fixtures/part.yaml
@@ -69,6 +69,7 @@
     name: 'Widget'
     description: 'A watchamacallit'
     category: 7
+    salable: true
     assembly: true
     trackable: true
     tree_id: 0
@@ -83,6 +84,7 @@
     name: 'Orphan'
     description: 'A part without a category'
     category: null
+    salable: true
     tree_id: 0
     level: 0
     lft: 0
@@ -95,6 +97,7 @@
     name: 'Bob'
     description: 'Can we build it?'
     assembly: true
+    salable: true
     purchaseable: false
     category: 7
     active: False
@@ -113,6 +116,7 @@
     description: 'A chair'
     is_template: True
     trackable: true
+    salable: true
     category: 7
     tree_id: 1
     level: 0