Action plays a central role in entrepreneurship and entrepreneurship education. Based on action regulation theory, we developed an action-based entrepreneurship training. The training put a particular focus on action insofar as the participants learned action principles and engaged in the start-up of a business during the training. We hypothesized that a set of action-regulatory factors mediates the effect of the training on entrepreneurial action. We evaluated the training's impact over a 12-month period using a randomized control group design. As hypothesized, the training had positive effects on action-regulatory factors (entrepreneurial goal intentions, action planning, action knowledge, and entrepreneurial self-efficacy) and the action-regulatory factors mediated the effect of the training on entrepreneurial action. Furthermore, entrepreneurial action and business opportunity identification mediated the effect of the training on business creation. Our study shows that action-regulatory mechanisms play an important role for action-based entrepreneurship trainings and business creation.