jats:p Abstract. The shift toward transdiagnostic and dimensional approaches to psychopathology research has created a growing need for psychometric assessments that reflect this conceptualization. We aimed to test whether an omnibus measure of psychopathology, the Social Behavior Questionnaire (SBQ), has suitable properties to serve as a dimensional, transdiagnostic assessment. We used an item response theory (IRT) approach to evaluate the reliable ranges of measurement of the psychopathology dimensions measured by the SBQ. For the dimensions of attention-deficit hyperactivity disorder (ADHD), Prosociality, Internalizing, and Externalizing, the SBQ can provide a reliable measure for below average to very high levels in a normative sample. </jats:p>