Summary: A 1978 report, "An Assessment of the Department of Housingand Urban Development's Experimental Housing Allowance Program (EHAP)," recognized that carefully designed and operated social experiments offer useful techniques for gaining information necessary to make informed decisions on major public policy issues. The report cautioned, however, that social research and development is in its early stages and, by its very nature, has certain limitations when projecting beyond the experiment. The EHAP Program represented a major effort on the part of the Department of Housing and Urban Development (HUD) to experiment with the concept of direct cash assistance to determine the feasibility and desirability of a national housing allowance program. Although EHAP will provide a wide range of information on housing markets and the behavior of low-income persons that has not been available before, it will not provide answers to the principal research questions initially posed. The experimental sites lacked the characteristics typical of major urban areas where a housing allowance program would be most needed. HUD did not clearly apprise Congress from the outset of the experimental limitations and raised its expectations too high. The question of confidentiality in social research became a real issue; until other review methods are developed, the extent to which data provided as part of a social experiment are to be considered confidential must be determined on a case-by-case basis.