This paper investigates why and how founding entrepreneurs bond with their ventures. We develop and test theory about the nature of bonding in a functional magnetic resonance imaging (fMRI) study of 42 subjects (21 entrepreneurs and 21 parents). We find that entrepreneurs and parents show similar signs of affective bonding, that self-confidence plays a role in bonding style, and that the degree to which entrepreneurs include their ventures in the self and to which parents include their child in the self influences their ability to make critical assessments. Our findings suggest that bonding is similar for entrepreneurs and parents and that venture stimuli influence reward systems, self-regulatory functions, and mental factors that are associated with judgment.