How group personality composition affects person and group outcomes: An integrative analysis using the group actor–partner interdependence model.

= 26.61, 51% female) who formed 108 four-person groups and engaged in four different group tasks. Our findings yield three key insights: (a) At the person level, people's own trait levels were the main drivers of their behaviors, experiences, and performance. (b) At the group level, personality composition affected different outcomes than at the person level, with agency playing an overall more important role for group behaviors and experiences. (c) Notable composition effects at both levels emerged for conflict behavior: People who were similar to their group in terms of agency were more engaged in conflicts, and groups whose members had similar agency levels were more likely to experience conflicts as a whole. We contextualize our findings within a theoretical framework to better understand when and how personality composition in social interactions is important, and we review methodologies to capture its multifaceted components. (PsycInfo Database Record (c) 2026 APA, all rights reserved).