For a long time, research on entrepreneurship was based on Rational Choice Theory which suggests an exclusively rational-economically acting entrepreneur. The option that emotions could influence the decision-making process of entrepreneurs was neglected in empirical research until the 1980s. Initiated by the approach of Behavioral Economics, the number of studies that deal with the effects of emotions in organizations has risen strongly in the last ten years. A number of studies demonstrated the positive influence of positive emotions on attention, perception or decision making. Although this underlines the importance of considering emotions in entrepreneurship research, research so far has mainly neglected the entrepreneur’s emotions and their affects on business performance. The following study focuses on the affects of joy of entrepreneurship on the development of workplaces – mediated by business performance. It makes a unique contribution to the literature by empirically testing the theoretical concept of reciprocal determinism in the case of entrepreneurs’ emotions using a longitudinal study.