MaryMo-- It does work for more than one mouse at a time and they will not be able to get out because the sides of the pail are too slippery. Only thing is you need to check the pail every day because you don't want the mice to be in there together too long because they could be mean to each other ....I know it sounds crazy but I've seen more than one in the pail and usually they are just ignoring the other but once, one of the mice had hurt the other one. Made me feel bad but the alternatives were worse. Just look at my avatar.