A new theory of interaction within small groups posits that group members initiate actions when tension mounts between the affective meanings of their situational identities and impressions produced by recent events. Actors choose partners and behaviors so as to reduce the tensions. A computer model based on this theory, incorporating reciprocal exchanges and actions toward the whole group, was used to generate 1,000 interactions in 500 virtual juries. Behaviors of modeled jurors matched the instrumental and expressive content of behaviors among actual jurors during observed deliberations. The system also reproduced sex differences among jurors, both in behavioral content and in levels of participation. Additionally, the system reproduced the domination of small-group interaction by a few active participants. Plausible changes in outcomes resulted when the system was used to analyze groups other than juries. These results indicate that the theory and model can advance research on small-group processes. (Contains 1 table, 4 figures and 1 footnote.)