Military duty places high demands on the soldiers' social adaptability and competences. Avoidant personality traits can lead to interpersonal conflicts and at least to mental disorders. 192 German Armed Forces soldiers were treated in a multimodal inpatient psychiatric treatment setting at a Bundeswehr hospital between 2007 and 2010. 129 of these patients received a social skills group training (group training of social competence [GSC]) as part of this setting. A comparison group (n=63) did not participate but got unspecific treatment elements instead. The Symptom Checklist 90-Revised (SCL-90-R) and the Inventory on Competence and Control Beliefs (Fragebogen zu Kompetenz- und Kontrollüberzeugungen [FKK]) were applied. Symptom severity in the SCL-Global Severity Index, sum scale of the SCL-90-R and the four primary scales of the FKK showed significant improvements both immediately after treatment and at follow-up. No significant influence of the form of treatment (with/without GSC), age, gender, diagnosis, and deployments on the treatment result was established in the analysis of covariance. The data suggest that an inpatient psychiatric treatment setting focused on avoidant personality traits has a favorable effect on psychiatric symptom severity in military personnel. Social skills group training as a treatment component does not seem to be significantly superior to the standard setting.