This study investigates differences in the diversity of cooperation partners used for innovation‐related activities (i.e., search breadth) between family and nonfamily small and medium‐sized enterprises (SMEs), as well as within the group of family SMEs. The results generally confirm our hypotheses derived from the behavioral theory of the firm. Specifically, we show that family SMEs have a lower search breadth than their nonfamily counterparts. Our findings further illustrate how attributes of the CEO (level of education) and the top management team (nonfamily management involvement and educational background diversity) relate to the search breadth of family SMEs.