The present study investigated gender differences in psychosocial functioning among clients mandated to substance abuse treatment. In the current study, 210 probationers' self reports of depression, anxiety, self esteem, decision-making, life beliefs, role modeling, cooperation, and AIDS risky behavior were gathered. Ratings were collected at intake as well as midway and toward the end of the residential phase of treatment. A series of growth curve models were used to examine changes in psychosocial functioning across these time periods. Improvements were recorded in several areas of psychosocial functioning over the course of treatment (including anxiety, depression, self esteem, decision-making, role modeling, and life beliefs). Importantly, significant gender by time interactions indicated that females showed greater rates of change than their male counterparts in such areas as self esteem, decision-making, and role modeling. The importance of psychosocial change and the implications of these gender differences are discussed.