Asch's work has had a profound impact on how psychologists think about and study social influence in groups. To appreciate this impact, we must go beyond his classic conformity experiments and consider his broader theoretical framework. This article examines 4 of Asch's ideas that have proven to be particularly influential in later efforts to understand social influence in groups: (a) Social interaction depends on individuals' ability to represent others' positions, define themselves as members of the same group, and regulate their behavior in terms of the norms and values of the group; (b) independence is critical to effective group functioning; (c) independence and conformity are not simply mirror images that can be explained in terms of a unitary psychological process; and (d) change of meaning is an important mechanism of social influence. Finally, Asch's role as a theorist and researcher in the wider area of group dynamics is considered.