The Survey of Income and Program Participation (SIPP), a national household survey of the noninstitutionalized United States population, is designed to provide information on income and government program participation. Person and family characteristics that may influence income and program participation are also available from the SIPP. The survey collects data which helps explain the socio-economic process in the U.S. and aids federal agencies in formulating and evaluating policies and programs in the areas of income and social welfare.