<p>To unravel the impact affect has on family business behavior, this paper studies the relationship between positive affect and decision commitment in top management teams of family firms. Specifically, we argue that this relationship is mediated by the degree of collective psychological ownership within the team, referring to the collectively held feeling that a target of ownership (or a piece of that target) is collectively “ours”. We empirically tested this proposed research model through a quantitative, survey-based approach. In particular, we hand-collected a unique multiple-respondent dataset of 212 top managers from 45 Belgian family firms. Based on the results, we can confirm that a high level of positive collective affect in a family firm top management team increases their decision commitment, meaning that they accept the strategic decisions made and intend to cooperate in carrying them out. Moreover, this relationship is indeed mediated by the team’s collective psychological ownership level. With these findings, we provide contemporary insights into the way in which affect impacts strategic decision-making, which is an important (family) firm outcome. As such, this study advances knowledge on the impact internal emotional dynamics have on family firm behavior.</p>