First published in 1985. This book presents a new way to ask an old question. Many fields have considered the nature of the influence that members of a group exert on the course of social events. Social science provides another way to examine this issue. Moreover, social science has a particular strength: It helps us to phrase questions more precisely than before, it encourages us to follow a line of reasoning systematically, and it requires us to evaluate our ideas in light of a particular kind of evidence. The authors want to use these strengths to explore systematically the ways that factors in the person and in the environment together may shape the emergence of social behavior.