I found this thread which seems to answer my question, but I'm not sure why LLBLGen doesn't work as expected:

http://www.llblgen.com/tinyforum/Messages.aspx?ThreadID=3694

My example:

For Each entity as SomeEntity in LotsaEntities
   If (entity.SomeField = False) Then
      entity.Fields.State = EntityState.Deleted
   End If

Next

adapter.SaveEntityCollection(LotsaEntities)

Why doesn't SaveEntityCollection remove the entities marked as Deleted? Am I doing something wrong?

Because that's not supported. If you want to delete an entity, call the methods which delete an entity or a group of entities. This to make sure you delete what you want to delete

Otis wrote:

Because that's not supported. If you want to delete an entity, call the methods which delete an entity or a group of entities. This to make sure you delete what you want to delete

If anyone is curious, this worked.. (Generics rule)

Dim entitiesToDelete As New System.Collections.Generic.List(Of Integer)

For Each entity as SomeEntity in LotsaEntities
   If (entity.SomeField = False) Then
      entitiesToDelete.Add(entity.EntityId)
   End If
Next

Dim deleteBucket As New RelationPredicateBucket()
deleteBucket.PredicateExpression.Add(PredicateFactory.CompareRange(SomeEntityFieldIndex.EntityId, entitiesToDelete))

adapter.DeleteEntitiesDirectly("SomeEntity", entitiesToDelete)