External corporate venturing has received significant attention in both scholarly journals and business press articles. However, there has been little investigation regarding behavioral elements that motivate firms to commit to a venturing portfolio. We utilize the behavioral theory of the firm literature to hypothesize that aspiration-relative performance influences commitment to an external venturing portfolio, such that performance above aspirations leads to decreased commitment, and performance below aspirations leads to increased commitment. We then incorporate the threat-rigidity literature and propose that managerial risk-taking proclivity and environmental dynamism moderate these relationships. We find support for most of our hypotheses.