We examined the psychometric properties of the Behavioral Inhibition Questionnaire (BIQ; Bishop, Spence, & McDonald, 2003), a rating scale for children's behavioral inhibition. Parent and teacher ratings, parent interviews, and laboratory observations were obtained for 495 preschoolers. Confirmatory factor analysis yielded 6 factors, each reflecting the BIQ's subscales, and all loading onto a second-order general dimension. Model fit was acceptable for parent ratings, but only marginal for teacher ratings. The convergent and discriminant validity of the BIQ was examined by using a multitrait-multimethod approach. Results indicate that the BIQ displays evidence of reliability and validity that can complement observational paradigms.