Mesh "expands" in object mode? As you can see in the above image, my mesh in edit mode, or at least certain parts of it, exist in the size intended for everything to be. But it sort of starts to "expand" and clips through other parts of the mesh in object mode. 

Why is this, and how do I fix it?

edit: here is the modifier tab
Things changing when entering/exiting edit mode are usually due to modifiers. Try disabling them to see if any is affecting your mesh on object mode.

As you have an armature modifier on the stack, I'd guess that some bone is scaled differently from (1,1,1), and that scales its assigned vertices.