Conformity--defined here by the fact that an individual displays a particular behavior because it is the most frequent the individual witnessed in others--has long been recognized by social psychologists as one of the main categories of social influence. Surprisingly, it is only recently that conformity has become an active topic in animal and comparative biology. As in any new and rapidly growing field, however, definitions, hypotheses, and protocols are diverse, not easy to organize in a coherent way, and sometimes seriously in conflict with one another. Here we pursue greater coherence by reviewing the newer literature on conformity in behavioral ecology and evolutionary biology in light of the foundational work in social psychology. We suggest that the knowledge accumulated in social psychology can be exploited by behavioral ecologists and evolutionary biologists to bring conceptual clarity to the field, avoid some experimental pitfalls, and help design new and challenging experiments. In particular, we propose that the notions of "informational" and "normative" conformity that, until now, have been little recognized in recent literature can resolve some important controversies. In turn, research on animal culture should be of great interest to social scientists, because understanding human culture and human uniqueness requires an evolutionary analysis of our cognitive capacities and their evolutionary origins. Our review suggests excellent opportunities for social and natural scientists to join forces in building an interdisciplinary and integrative approach to the pervasive phenomenon of conformity. (Contains 7 footnotes, 1 tables, and 2 figures.)