Compliance is one of a variety of ways in which people can be influenced by others. Two meanings have been attached to the term. Investigators such as Leon Festinger, Herbert Kelman, and Paul Nail define compliance as a change in public behavior without private acceptance. (As discussed below, when others influence both public behavior and private acceptance, the form of social influence is called conversion or internalization.) More recently, Robert Cialdini has offered a second definition of compliance that ignores the distinction between public and private. He defines compliance as acquiescence to a request. Each definition has generated a different set of questions and research findings. This entry examines both definitions.