One kind of social control is known as self-help: the expression of a grievance by unilateral aggression such as personal violence or property destruction. It is commonly believed that self-help was largely displaced by law in the Western world during the Middle Ages, and that it has survived primarily in the traditional -- especially stateless -- societies studied by anthropologists. In fact, much of the conduct classified as crime in modern societies such as the United States is similar to these traditional modes of social control and may properly be understood as self-help. Several implications follow, including the possibility of predicting and explaining a significant amount of crime with a sociological theory of self-help, itself a branch of the theory of social control. (Author abstract)