•Using a longitudinal field experiment, we find that an entrepreneur mentor increases the likelihood of joining a startup.•The entrepreneur mentor effect was significantly stronger for students whose parents were not entrepreneurs.•Performance data suggests that social influence is not encouraging “worse” quality entrepreneurship.•We contribute by examining the interaction between multiple sources of social influence.•We contribute by using a randomized field experiment to overcome the endogenous process of tie formation. How do different sources of social influence impact the likelihood of entrepreneurship? We examine this question in the setting of an entrepreneurship class in which students were randomly assigned to receive mentorship from either an entrepreneur or a non-entrepreneur. Using a longitudinal field experiment with a pre-test/post-test design, we find that randomization to an entrepreneur mentor increases the likelihood of entrepreneurial careers, particularly for students whose parents were not entrepreneurs. Additional analysis shows the mentor influences the decision to join an early-stage venture, but not to become a founder. Performance data suggests that entrepreneurial influence is not encouraging “worse” entrepreneurship and may have helped students in joining or founding better-performing ventures. We contribute to the literature on social influence in entrepreneurship by examining the interaction between multiple sources of social influence and by using a randomized field experiment to overcome the endogenous process of tie formation.