Efforts to provide affordable housing are occurring at a time of great change. The responsibilities for implementing affordable housing are increasingly shifting to state and local actors. The market and demographic changes in the country are complicating the picture, as sprawling jobs-housing patterns and downtown revivals in some places are creating demand for affordable housing for working families and immigrants in both cities and suburbs. To help state and local leaders design fresh solutions to today’s affordable housing challenges, The Brookings Institution Center on Urban and Metropolitan Policy and the Urban Institute joined forces to examine the lessons of seven decades of major policy approaches and what these lessons mean for local reforms. This executive summary of the full report, funded by the John S. and James L. Knight Foundation, finds that past and current efforts to expand rental housing assistance, promote homeownership, and increase affordable housing through land use regulations have been uneven in their effectiveness in promoting stable families and healthy communities. The findings suggest guiding principles for local action, with important cautions to avoid pitfalls. Although there are serious gaps in the housing research literature, evidence on the experience of the past has a lot to offer today’s policymakers and practitioners. The following matrix provides an overview of our key findings on the effectiveness of federal housing programs in meeting the seven policy goals. Affordability is the central challenge for rental-assistance policy. This means that building more rental units is not necessarily the solution to the housing problems facing low-income renters. Subsidizing the rents for existing units is much less costly than building new units.