Plain Language SummaryThis scientific study examines the association between psychobehavioral factors and somatic symptom reporting in a large sample of psychosomatic outpatients. We investigated the association of established and possible additional psychobehavioral criteria for somatic symptom disorder (SSD) as defined in the DSM-V. The study included 6,491 patients from a psychosomatic outpatient center over a 12-year period. The participants completed self-report questionnaires to assess somatic symptom reporting and psychobehavioral factors. The results showed that the B-criteria of SSD were associated with somatic symptom reporting, indicating the validity of these criteria in clinical practice. Other psychobehavioral factors, such as depressive symptoms and impaired activity and participation, as well as sociodemographic factors such as age and gender were also associated with somatic symptom reporting but to a much lesser extent. This study has limitations, including its retrospective and cross-sectional design, reliance on self-report measures, and the need for further research using longitudinal data and clinician-rated assessments to complement self-report data. However, our research highlights the importance of psychological symptomatology in individuals who report somatic symptoms. These findings may inform future diagnostic criteria and treatment approaches for individuals with SSD and improve treatment and patient outcomes.