Theoretical explanations for family firm underinvestment in R&D relative to nonfamily firms remain nascent. We revisit this question using a refinement to the behavioral agency model (BAM)—the mixed gamble—that allows us to examine the socioemotional trade‐offs that R&D represents for the family firm and how this differentiates their R&D investment decision from nonfamily firms. We do so in an empirical context where R&D investment is of greatest importance—high‐technology industries. Moreover, we examine three contingencies that allow us to explore heterogeneity across family firms in their R&D decisions due to their effect upon the family's socioemotional wealth mixed gamble: institutional investor ownership, related diversification, and performance hazard.