"Dog rehabilitation" is Millan's primary profession, which is portrayed on the program through real-life cases with owners and their dogs. Millan opened the Dog Psychology Center in the mid-1990s, prior to his success with television. Cesar's strongest interest is in rehabilitating aggressive dogs, and he holds a special fondness for what he refers to as the "power breeds," such as pit bulls and rottweilers.
Via word of mouth, in 1994 he came to the attention of celebrities Will Smith and his wife Jada Pinkett Smith (whom Millan cited as being responsible dog owners), who began recommending Millan to many other celebrities and also mentored him in other ways, helping to improve his English as well as becoming good friends.