The psychometric properties of a German version of the Questions About Behavioral Function Scale (QABF) (Matson & Vollmer, 1995) were examined in a sample of 522 individuals with intellectual disabilities residing in large facilities participated. The factor structure was first examined by exploratory factor analysis, yielding a five-factor-solution that was identical to the one described by the authors of the QABF and was statistically and clinically meaningful. Furthermore the factor structure was validated by confirmatory factor analysis. Fit indices indicated satisfactory model fit. Internal consistency was found to be good with Cronbach's alphas ranging from 0.84 to 0.62.Interrater reliability was fair with intraclass correlations ranging from 0.66 to 0.58. (Contains 1 figure and 6 tables.)