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.