A renewed emphasis has been placed on mixed-income housing through HUD’s HOPE VI program and the bipartisan consensus to end the concentration of low-income people in public housing. Through an analysis of seven successful mixed-income housing developments, this article defines a research and learning agenda for academics and practitioners in the field. Preliminary analysis indicates that successful mixed-income developments must be well located and excellent in their design and management if they are to attract renters who have location choices. Mixed-income housing works best where there are sufficient units aimed at the higher-income renters to create a critical mass of market units and where there are no differences in the nature and quality of the units being offered that are due to the income of the renters.