Recent gains in understanding the effects of childhood maltreatment on the development of the brain and nervous system, combined with the revelation that nearly all psychiatric neuroimaging studies have had an unrecognized confound in childhood maltreatment, imply the possibility that psychotherapy treatment effectiveness studies have been similarly confounded by childhood maltreatment. This study examines whether treatment-seeking adults exposed to childhood maltreatment respond differently to psychotherapy than do individuals who report no history of childhood maltreatment. Response to therapy is conceptualized in this study as reduction in symptom measures pre- and post- treatment, as well as client dropout. It is hypothesized that people with a history of childhood maltreatment experience psychotherapy differently, may experience differences in symptom reduction and be more likely to drop out of treatment, than people with no history of childhood maltreatment. The current study examines psychotherapy effectiveness in symptom reduction and dropout rates of clients who experienced childhood maltreatment as compared to those with no history of childhood maltreatment.