The papers and discussions in this volume were presented in a conference held at the Brookings Institution in November 1963 to explore the problems of appraising the benefits that are likely to accrue from proposed public investment projects. To throw light on this question from several directions, papers were commissioned to deal with it in seven contexts: research and development expenditures, outdoor recreation projects, education programs, federal aviation expenditures, highway programs, urban renewal projects, and public health programs.