The first part of the chapter describes the several deleterious effects of psychological disunity on sociology and anthropology, which at times have borrowed various conflicting psychological concepts and propositions. Through such borrowing the social sciences have been infected by this disunity, which in turn has contributed to their own disunified state. The area of social change illustrates the confusion wrought by conflicting psychological theories regarding the determinants of behavior. The second part of the chapter describes the potential influence that the social sciences can exert toward the unification of psychology. Data from three substantive areas illustrate how inductions from events in various societies can be used to formulate psychological propositions crucial for the unification of psychology.