Objective: We previously reported that a history of abuse was associated with a poorer response to combination treatment in the Treatment of Resistant Depression in Adolescents study (TORDIA). We now report on the nature and correlates of abuse that might explain these findings. Method: Youth who did not benefit from an adequate selective serotonin re-uptake inhibitor (SSRI) trial (N = 334) were randomized to one of the following: an alternative SSRI; an alternative SSRI plus cognitive behavior therapy (CBT); venlafaxine; or venlafaxine plus CBT. Analyses examined the effect of history of abuse on response to the pharmacotherapy and combination therapy. Results: Those without a history of physical abuse (PA) or sexual abuse (SA) had a higher 12-week response rate to combination therapy compared with medication mono-therapy (62.8% versus 37.6%; odds ratio [OR] = 2.8, 95% confidence interval [CI] = 1.6-4.7, p less than 0.001). Those with a history of SA had similar response rates to combination versus medication monotherapy (48.3% versus 42.3%; OR = 1.3, 95% CI = 0.4-3.7; p = 0.66), whereas those with history of PA had a much lower rate of response to combination therapy (18.4% versus 52.4%, OR = 0.1; 95% CI = 0.02-0.43). Even after adjusting for other clinical predictors, a history of PA moderated treatment outcome. Conclusion: These results should be considered within the limitations of a post hoc analysis, lack of detailed assessment of abuse and other forms of trauma, and neuropsychological status. Depressed patients with history of abuse, especially PA may require specialized clinical approaches. Further work is needed to understand by what mechanisms a history of abuse affects treatment response. Clinical Trial Registry Information: Treatment of SSRI-Resistant Depression in Adolescents (TORDIA); NCT00018902; http://www.clinicaltrials.gov. (Contains 2 tables and 1 figure.)