The American Housing Survey (AHS) measures physical adequacy, a concept related to, but different from, housing quality. The U.S. Department of Housing and Urban Development developed this measure to assess the extent to which the housing stock met the standard of “a decent home and a suitable living environment,” established by the Housing Act of 1949. The AHS definition of physical adequacy is complex; any 1 of 14 different situations can result in the classification of a unit as having severe physical problems. According to this measure, very few American housing units have serious physical problems. In each of the 3 years studied (2005, 2007, and 2009), the percentage of occupied housing units that were severely inadequate was less than 2 percent.