This paper reviews the role of urban planning in ensuring the provision of adequate affordable housing through the method of ‘inclusionary housing’, also known as ‘inclusionary zoning’, and considers its potential as a tool in the prevention and solution of homelessness. Whilst the complexity of homelessness means that it cannot be explained fully or solved solely by the provision of affordable housing, such housing is nonetheless a vital requirement in the fight against homelessness. Inclusionary housing, first developed in the United States, requires that a given share of new housing has to be affordable to low- and moderate-income households. It is not common in Europe at present but is being considered as a way of increasing the supply of affordable housing.