I think it's easier when you get the cats at the same time; however, it also depends on the temperments of both cats. At various times we have adopted 2 kittens at a time; then when one passed away we did get another one and they got along fairly well. Right now I have a cat that's 10+ years old and I seriously doubt that she would get along well with another cat; and especially since my DH was not happen when I brought TJ home to live; however, since we downsized to a 2-bedroom apt. and I spent several months in Rehab off and on since we moved to MA; DH has had to take care of her and he has mellowed towards her; although she is definitely MY cat, who thinks she is part dog as she always follows me around and has to be near me. If something happened to her, I don't think I would get another cat, as we are getting on in years; but cats can be such terrific companions.