Edwin Sutherland developed differential association theory in 1939 in his text Principles of Criminology. He offered an interpersonal explanation of behavior based on three major assumptions: 1) human behavior is flexible; 2) learning occurs primarily in small, informal groups; and 3) the learning of behavior takes place through collective experiences as well as through specific situations. Differential association stands as a good formulation of the importance of peer pressure. Differential association represents a theory that explains the onset of delinquent behavior and points to the fact that juveniles learn delinquent behavior from peer groups. Placing juveniles in a deviant group creates an association which perpetuates deviant behavior. Peer-group pressure stands as the strongest force on the lives of young people and represents the source of most delinquent behavior.
There are several basic principles underlying differential association, as set forth by Sutherland. This theory assumes that the individual becomes delinquent because of an excess of definitions favorable to violations of law over definitions unfavorable to violations of the law. The peer group presents shoplifting as an activity with more definitions favorable to the activity than not, seeing i