Emily was a stray cat living on the mean streets of Baltimore. Once I got her from the animal rescue place she REFUSES to go outside anymore. A little while ago one of my window screens popped out of the window while I was at work. I thought that she would have escaped but I came into the apartment and she was sleeping on the couch. Even if I hold the door open for her, she refuses to go anywhere near it. So I wouldn't worry, I am sure that Lilly will adjust to living inside without any problems.