Inclusionary zoning, also known as inclusionary housing, is an American term which refers to municipal and county planning ordinances that require a given share of new construction to be affordable by people with low to moderate incomes. The term inclusionary zoning indicates that these ordinances seek to counter exclusionary zoning practices, which aim to exclude low-cost housing from a municipality through the zoning code. In practice, these policies involve placing deed restrictions on 10%-30% of new houses or apartments in order to make the cost of the housing affordable to lower-income households. The mix of "affordable housing" and "market-rate" housing in the same neighborhood is seen as beneficial by political activists. Inclusionary zoning is a tool for local municipalities in the United States to allegedly help provide a wider range of housing options than a free market provides on its own. Many economists consider the program as a price control on a percentage of units, which negatively impacts the supply of housing.
Most inclusionary zoning is enacted at the municipal or county level; when imposed by the state, as in Massachusetts, it has been argued that such laws usurp local control. In such cases, developers can use inclusionary zoning to avoid certain aspects of local zoning laws.
Read more about Inclusionary Zoning: Historical Background, Differences in Ordinances, Alternative Solutions, Controversy, Inclusionary Zoning in Practice