The U.S. Social Security Disability Insurance (SSDI) program is designed to provide income support to workers who become unable to work because of a severe, long-lasting disability. At present, nearly nine million former workers receive SSDI benefits, following several decades of rapid growth. As the program has expanded, observers have debated the degree to which this program growth is due to, on the one hand, past policy changes and anticipated growth in the insured population, or on the other hand, declining returns to labor force participation among low-skilled workers. Underscoring the important role of labor markets is the evidence that SSDI payments in Appalachia responded counter-cyclically to local earnings shocks caused by the coal boom and bust of the 1970s and 1980s (Black, Daniel and Sanders, 2002). More recently, Linder and Burdick (2013) show that the unemployment rate was positively associated with disability benefit claiming during and after the 2001 recession. A finding that SSDI receipt is sensitive to economic cycles is of concern for several reasons. The first is that there is little evidence that the incidence of severe disability is itself countercyclical. Because of this, SSDI is designed to insure against permanent earnings shocks due to onset of disability, and not transitory earnings shocks due to labor market conditions. Its strict eligibility rules, lengthy application processing times, and implicit work disincentives reflect this purpose, and indeed very few SSDI beneficiaries ever return to substantial labor market activity. It is thus problematic if displaced and discouraged workers turn to the SSDI program when they are in need of temporary assistance, since they are unlikely to ever return to work once the labor market recovers. One explanation for these business cycle effects is that they are driven by conditional applicants; that is, workers with health impairments who would prefer to remain in the labor force, but who would apply for SSDI benefits if they lost their present job (Autor and Duggan, 2003). Because applying for public SSDI benefits in the United States requires that one’s earnings are below the threshold defining substantial gainful activity (SGA), the opportunity cost of applying for benefits is reduced when one becomes unemployed. Thus, not only should there be more SSDI applicants during economic downturns, there should be notable compositional differences between those who apply during economic expansions and those who apply during economic recessions. Using survey data, Coe and Rutledge (2013) find that SSDI applicants during recessions have higher past earnings and more recent work experience (see also Lindner and Burdick, 2013). In this study, we use administrative data to estimate the effect of labor market conditions, as measured by the unemployment rate, on the number of SSDI applications, the number and composition of initial allowances and denials, and the timing of applications relative to disability onset. We analyze the period of the Great Recession, and compare this period with business cycle effects over the past two decades, from 1992 through 2012. Our analysis isolates the quantity and composition of applicants who are induced to apply for SSDI benefits when labor market opportunities decline, and therefore provides important new evidence about the group for whom SSDI application is a substitute for labor force participation, and their impact on the SSDI program.