Despite decades of research, biomarker identification for psychiatric disorders has been lacking and the development of effective interventions has been limited. High rates of comorbidity and shared pathophysiologic mechanisms across disorders has redirected efforts towards the identification of core psychological processes that lead to psychopathology and to the development of interventions that can be applied transdiagnostically. This seminar will focus on this new conceptualization by focusing on systems for social processes such as perception and interpretation of mental states and attachment. Information will be conveyed on biopsychological underpinnings of psychiatric disorders involving defining social interaction problems such as autism spectrum disorders, borderline personality disorders, and social anxiety disorder. A special focus will be on advantages of a transdiagnostic approach for diagnosis and treatment of social interaction disorders.