The purpose of this meta analysis was to examine the moderating impact of substance use disorder as inclusion/exclusion criterion as well as the percentage of racial/ethnic minorities on the strength of the alliance-outcome relationship in psychotherapy. It was hypothesized that the presence of a Diagnostic and Statistical Manual of Mental Disorders (DSM) Axis I substance use disorder as a criterion and the presence of racial/ethnic minorities as a sociocultural indicator are moderately correlated client factors reducing the relationship between alliance and outcome. A random effects restricted maximum-likelihood estimator was used for omnibus and moderator models (k = 94). The presence of (a) substance use disorder and (b) racial/ethnic minorities (overall and specific to African Americans) partially moderated the alliance-outcome correlation. The percentage of substance use disorders and racial/ethnic minority status was unexpectedly highly correlated in the present treatment research samples. Sociocultural contextual variables should be considered along with a DSM Axis I diagnosis of substance use disorders in analyzing and interpreting therapy process variables such as the alliance. (PsycINFO Database Record (c) 2013 APA, all rights reserved).