All-male, all-female, and mixed groups were observed for possible differences in interactional style. The groups met for 5 11/2-hr unstructured meetings. Portions of the tape-recorded sessions were analyzed by the General Inquirer computer-aided content analysis system. Leadership, defined as rank order of Ss initiating interaction, showed greater variation along sessions in the female than in the male group, whereas in the mixed group the males initiated and received more interaction than the females. Exercise of power, defined as amount of talking to the group as a whole rather than to individuals, occurred more often in the male groups than in the female. In the mixed groups, the female pattern did not change, but the males addressed the group as a whole less often in mixed groups. A 3rd difference was found on the variable of intimacy and openness. Female group members revealed more information about themselves and their feelings than the male group members. In the mixed group, males shared more about themselves than in the all-male group. Sex role pressures are considered to be a contributing factor to the results. (PsycINFO Database Record (c) 2012 APA, all rights reserved)