Research Summary: We argue that willingness (attitude toward risk, return, and socioemotional wealth), ability (extent of control), and resource availability influence the internationalization of family firms. We hypothesize that the internationalization of family firms led by founding and later generation family members differs from the internationalization of nonfamily firms and from each other and that knowledge‐based resources moderate the relationship. Longitudinal analysis of 4,925 firm‐year observations of S&P 1500 manufacturing firms from 2002 to 2008 shows that compared to nonfamily firms, family firms run by founding (later generation) family members internationalize less (more). Knowledge resources increase (decrease) the internationalization of founder‐led (later generation) family firms. Overall, how family ownership influences firm behavior is likely to vary as much by its type as its amount. Managerial Summary: We explore the internationalization of family firms based on a sample of S&P 1500 manufacturing firms from 2002 to 2008. Compared to nonfamily firms, family firms run by founding family members internationalize less, and family firms run by later generation members internationalize more. However, as knowledge resources increase, the internationalization of founder‐led family firms increases, whereas the internationalization of firms led by later generation family members decreases. Therefore, our findings suggest that knowledge resources can facilitate or hamper international expansion in family firms, depending on the generation of family control. These findings underscore the role of goals, governance, and resources as important drivers of differences in internationalization between family and nonfamily firms, as well as of variations in internationalization among family firms.