This study examined outcomes and attrition across three treatments for depression in relation to socioeconomic status (SES). The study was based on data available from the Treatment of Depression Collaborative Research Program (TDCRP) of the National Institute of Mental Health (NIMH; Elkin, 1994), a multisite collaborative study that examined the effectiveness of two forms of psychotherapy, cognitive behavior therapy and interpersonal psychotherapy, and pharmacotherapy. Results indicated that lower SES, measured by the Hollingshead Index of Social Position, was associated with less improvement across all three treatments for depression. The effect of SES on outcome did not differ by treatment modality. Contrary to expectations, SES was not associated with attrition. These findings suggest that there may be limitations in the use of these empirically validated treatments with lower SES depressed patients, as their improvement rates may be less than those of middle SES depressed patients treated by the same modalities. The results of this study also suggest that a standardized measure of SES may be more sensitive to SES differences in outcome than the more easily obtained measures of education or income. Suggestions are provided for additional research in this area to address the potential mediators and moderators of the association between SES and outcome.