Prior studies find sizable gaps between entrepreneurial intentions and subsequent actions. We extend models of entrepreneurial intentions by drawing on action phase theory to better understand how entrepreneurial intentions translate into actions. Our study focuses on the effects of implementation intentions on taking entrepreneurial action. The analysis uses two waves of survey data on 422 individuals, from the Swedish general population, who had an explicit interest in starting a business and who reported on their actions 6 months later. We test and find support for a moderated mediation model in which implementation intentions mediate the effects of goal intentions on taking entrepreneurial action. We further find the mediated effect to be even stronger for those confirming a strong intention to start a new business. We provide an in-depth discussion of the concept of implementation intention and an extensive research agenda.