Why are some welfare state programs more susceptible to retrenchment than others? This article brings new attention to this core question in the welfare state reform literature by examining why the major disability benefit program in the United States has proven resistant to austerity measures, while the comparable disability benefit program in Great Britain has been repeatedly scaled back. A comparative-historical analysis is provided following a most similar systems research design. Drawing on institutional and ideational theories of policy change, it is argued that structural differences between the two disability benefit programs mattered a great deal, as did the ability of political leaders in Great Britain to portray disability benefit recipients as members of an underclass, which proved critical for constructing the need for retrenchment.