Have to disagree with quotemander. I had a single rat, who was quite happy. When I wasn't home she was in her cage with a few toys, When I was home, she was either running around my computer desk, running over my girlfriend or running around the house in her hamsterball. My cat wasn't allowed near her during our snuggle times, but when she was in the ball we let them kinda go free. Kitty would stalk the ball, but our dogs would normally go and sniff at her causing her to run away before she could do anything. Old dog wasn;t even interested in hamster ball, puppy was, but he just wanted to sniff. He must sniff everything though. Bare in mind this was when I was a teenager, so I had alot of free time to let her be social with me and my friends. Growing up a bit with less free time I'm not sure it would work out as well. But if you didnt want to get 2, 1 could work if you spend time with them.