One night I heard this awful screaming outside and went out with a flashlight to find two raccoons fighting next to the coops, so yes. The pop door has one of those hasps that folds over itself and I put a carabiner through the loop. The side door has a small stall latch like you would put on a horse stall door. It has a loop that holds the sliding bar in place and I use a carabiner to lock it closed. The carabiner is spring loaded and easy for a human hand, but takes a larger grasp that raccoons would have a problem with. I have that kind of lock on every coop.