To estimate differences in post-treatment psychosocial functioning among treatment 'failures' (i.e. heavy drinkers, defined as 4+/5+ drinks for women/men) from two large multi-site clinical trials and to compare these levels of functioning to those of the purported treatment 'successes' (i.e. non-heavy drinkers). Separate latent profile analyses of data from two of the largest alcohol clinical trials conducted in the United States, COMBINE (Combined Pharmacotherapies and Behavioral Interventions) and Project MATCH (Matching Alcoholism Treatments to Client Heterogeneity), comparing psychosocial outcomes across derived classes of heterogeneous treatment responders. Eleven US academic sites in COMBINE, 27 US treatment sites local to nine research sites in Project MATCH. A total of 962 individuals in COMBINE (69% male, 77% white, mean age: 44 years) treated January 2001 to January 2004 and 1528 individuals in Project MATCH (75% male, 80% white, mean age: 40 years) treated April 1991 to September 1994. In COMBINE, we analyzed health, quality of life, mental health symptoms and alcohol consequences 12 months post-baseline. In Project MATCH, we examined social functioning, mental health symptoms and alcohol consequences 15 months post-baseline. Latent profile analysis of measures of functioning in both samples supported a three-profile solution for the group of treatment 'failures', characterized by high-, average- and low-functioning individuals. The high-functioning treatment 'failures' generally performed better across measures of psychosocial functioning at follow-up than participants designated treatment 'successes' by virtue of being abstainers or light drinkers. Current United States Food and Drug Administration guidance to use heavy drinking as indicative of treatment 'failure' fails to take into account substantial psychosocial improvements made by individuals who continue occasionally to drink heavily post-treatment.