The current study investigated the relationship between the psychological capital of entrepreneurs and the performance of their new ventures (i.e., revenue and employment growth). Entrepreneurs’ psychological capital was found to explain a significant amount of variance in new venture performance, above and beyond measures of financial capital, human capital and social capital. Further, the relationship between psychological capital and new venture performance was found to be enhanced by environmental dynamism, such that the relationship is most positive when dynamism is high, as opposed to low.