The current study draws on motivated information processing in groups theory to propose that leadership functions and composition characteristics provide teams with the epistemic and social motivation needed for collective information processing and strategy adaptation. Three-person teams performed a city management decision-making simulation (N=74 teams; 222 individuals). Teams first managed a simulated city that was newly formed and required growth strategies and were then abruptly switched to a second simulated city that was established and required revitalization strategies. Consistent with hypotheses, external sensegiving and team composition enabled distinct aspects of collective information processing. Sensegiving prompted the emergence of team strategy mental models (i.e., cognitive information processing); psychological collectivism facilitated information sharing (i.e., behavioral information processing); and cognitive ability provided the capacity for both the cognitive and behavioral aspects of collective information processing. In turn, team mental models and information sharing enabled reactive strategy adaptation.