Background The Schedule for Affective Disorders and Schizophrenia for School Age Children, Present and Lifetime Version (K-SADS-PL) is a commonly used diagnostic interview both in research and clinical settings, yet published data on the psychometric properties of the interview generated diagnoses are scarce. Aims To examine the convergent and divergent validity of the Norwegian version of the K-SADS-PL current diagnoses of anxiety disorders and attention deficit hyperactivity disorder (ADHD). Method Participants were 105 children aged 7-13 years referred for treatment at child mental health clinics and 36 controls. Diagnostic status was determined based on K-SADS-PL interviews with the mothers. Child and mother reported child symptoms of anxiety on the Multidimensional Anxiety Scale for Children and teachers reported anxiety symptoms on the Teacher Report Form. Mother and teacher reported on symptoms of ADHD on the Disruptive Behavior Rating Scale. Results Rating scale data from multiple informants in a clinical sample and healthy controls supported the convergent and divergent validity of K-SADS-PL anxiety diagnoses combined, and, specifically, the diagnoses of separation anxiety disorder, social phobia, and specific phobia. Support was also observed for convergent and divergent validity of ADHD diagnoses, including the predominately inattentive subtype. Conclusion The K-SADS-PL generates valid diagnoses of anxiety disorders and ADHD.