The growing number of individuals suffering from a serious mental illness underscores the important role of interventions such as treatment, policies, and programs to support those in need. Such support efforts often interact in unanticipated ways. This paper considers the degree to which access to mental health treatment services affects participation in federal disability programs including the Supplemental Security Income and the Social Security Disability Insurance (SS(D)I) programs. Our main approach uses an identification strategy that leverages county-level variation in the number of mental health treatment establishments to estimate changes in access to mental health treatment on SS(D)I program participation—measured by applications and awards. We also explore a series of event studies and heterogeneity analyses. Our results show that an increase in mental health facilities increases participation in SS(D)I programs. A 10 percent increase in a county’s number of office-based mental health establishments increases the SSI application rate by 1.2 percent and the SSDI application rate by 0.7 percent. While the overall sample suggests that this does not translate to an increase in SS(D)I awards, we do find increases in awards in counties that have a higher proportion of residents below the poverty line. This suggests that increasing access to mental health resources can be a pathway through which people suffering from severe mental illness can be diagnosed and access social safety nets.