Existing studies of entrepreneurship focus on entrepreneurs whose individual contribution to wealth creation is typically trivial: self-employed persons. This paper investigates entrepreneurs whose individual contribution to wealth creation is enormous: billionaires. We explore the relationship between economic development, institutions, and these contrasting kinds of entrepreneurs. We find that the institutions consistent with self-employed entrepreneurs di¤er markedly from the ones consistent with billionaires. Further, only the latter are consistent with the institutions that underlie economic prosperity. Where well-protected private property rights and supporting, market-enhancing institutions flourish, so do billionaires. But self-employed entrepreneurs don't. Where private property rights are weakly protected and interventionist institutions flourish, so do self-employed entrepreneurs. But billionaires don't.