The present study investigated the effectiveness of a social skills training program with 131 socially-anxious psychiatric inpatients and outpatients. Ninety-six patients were admitted to the treatment condition: 20 of them dropped out during treatment; 35 patients were randomly assigned to the control group. The social skills training resulted in a decrease in social anxiety and an increase in social skills. Treatment effects were maintained 3 months after treatment. Predictors of treatment outcome immediately after treatment and after a 3-month period of follow-up were investigated. The results are discussed with reference to extending the treatment targets to include a more active expansion of real-life situations and to the implementation of the therapy program in a clinical setting.