Public markets were once essential parts of the cityscape and they are becoming so again. Markets serve several purposes, social, political, and economic, and so planners interested in multipurpose tools for development will be interested in public markets. Markets can help achieve a variety of goals including place-making, employment, and entrepreneurship. This article focuses on markets as tools of business incubation. Archival data and literature shows how important markets once were to cities. Ethnographically collected data from Chicago's Maxwell Street market illustrates the individual and structural factors that account for businesses created at the market. Rural and urban markets are emerging or being rehabilitated all over the country — this research helps planners understand the history of markets, their multi-disciplinary nature, and the circumstances of people creating businesses at markets.