We explore how variation in entrepreneurs’ displayed passion affects informal investor interest in start-up ventures by examining neural responses to entrepreneurs’ pitches using functional Magnetic Resonance Imaging (fMRI). We find that founders displaying high passion increase investor neural engagement by 39% and investor interest in the venture by 26% over those displaying low passion. A one standard deviation increase in neural engagement is associated with an 8% percent increase in investors’ interest in investing in a start-up company relative to the mean. Moreover, our findings indicate that neural engagement may account for some of the effect of founder passion on investor interest. Our study has implications for both research on, and the practice of, entrepreneurship.