Childhood phobias can be successfully treated using a variety of behavioral strategies, provided there has been a psychometrically sound assessment. Measures are also important for the evaluation of treatment efficacy and the testing of hypotheses generated by new ideas and theories of children's phobias. This paper outlines broad-based assessment procedures used in the evaluation of children's phobias, including the behavioral or problem-focused interview, the diagnostic interview, self-report inventories, caregiver completed instruments, behavioral observations, self-monitoring and physiological assessment. Reflecting recent theoretical and clinical advances in the study of childhood internalizing disorders, we also explore laboratory-based measures and family assessment measures. Particular attention is given to psychometric issues and developmental sensitivity in our discussion of these assessment procedures.