This study examined the psychometric properties of the German Self-Report and Parent Report Rating Scale for Anxiety Disorders (SRS-AD and PRS-AD), and a shortened teacher version of the PRS-AD (TRS-AD) in a large clinical sample. Data were collected from 585 children, adolescents and young adults with psychiatric disorders (aged 6–21 years), 821 parents and 378 teachers. Factorial validity, reliability and discriminating validity of the scales were examined and the agreement between different informants was assessed. Analyses were performed in the complete sample including a wide range of different psychiatric disorders as well as in a subsample of children, adolescents and young adults with anxiety disorders. Confirmatory factor analyses mostly supported a model with first-order factors according to the subscales and a second-order overall anxiety factor. Only for the SRS-AD analysed in the sample of participants with anxiety disorders, the results did not clearly favour a first-order solution with correlated factors according to the subscales or the second-order solution adopted for the other questionnaires. Internal consistencies for the total scale and subscales were mostly satisfactory. Significant mean differences between anxious and non-anxious participants were found for the mean total scores of the SRS-AD and PRS-AD, but not for the TRS-AD. The informant agreement was low-to-moderate. We concluded that the SRS-AD, PRS-AD and TRS-AD demonstrate satisfactory psychometric properties for use with clinically-referred children and adolescents.