Inclusionary zoning-requiring and encouraging developers to build some affordable housing in market-rate projects-is a growing but deeply contested practice. We evaluate the experience of inclusionary zoning programs in Los Angeles and Orange Counties, including their structure and elements, effectiveness in delivering affordable housing, and effect on housing markets and supply, to address the debate. We find that the programs vary but are not heavily demanding and include cost offsets. Low in-lieu fees, however, can be the weak link. Many of the mandatory programs are effective, if effectiveness is measured by comparing the affordable housing productivity of inclusionary zoning with other affordable housing programs. We found no statistically significant evidence of inclusionary zoning's adverse effect on housing supply in cities with inclusionary mandates. We conclude that critics underestimate the affordable housing productivity of inclusionary zoning, and overestimate its adverse effects on housing supply. Nonetheless, inclusionary zoning is no panacea and needs to be part of a comprehensive housing strategy. Improving access to affordable housing is always a key challenge for local governments. With regular cutbacks in both federal and state support for housing programs, the task keeps becoming more difficult. One local government-based response to the persistent affordable housing shortage in the context of declining funds is the policy of inclusionary zoning. Inclusionary zoning requires and encourages private housing developers to build a specified proportion-often ranging from 10% to 15% -of affordable housing units in market-rate projects. Although some scholars and Direct correcpondence to: Vinit Mukhija,

Inclusionary zoning (IZ), a controversial planning tool for supplying affordable housing, grew significantly during the 2000s' housing boom in the USA. We review the resultant scholarly literature on IZ. Our key reading is that IZ can include both tradeoffs and practical efforts to address them. There is also a need for additional research. More specifically, we find that IZ programs (i) have many components and vary considerably; (ii) can increase affordable housing production and social integration, but there can be a tradeoff between these goals; and (iii) can have slight adverse market effects, but cost-offsets can help mitigate the outcomes. Finally, we discuss the need for more research, particularly in-depth case studies and make suggestions.