Recent concern with population growth has begun to stimulate interest in the effect of crowding on humans. This report presents a model of crowding based on the concept of normative expectations concerning appropriate interaction distances. A study of acute experimental crowding was then conducted. Contrary to findings of prior research, the present study found that crowding produced arousal. Subsequent social behavior, however, was mediated by different sex‐specific group processes. In general, crowded male groups displayed a competitive, fragmented orientation, whereas crowded women formed cohesive, cooperative groups. Contrary to preliminary expectations, subjects were differentially effected by crowding based on their seating position in the crowded roo