Reviewed the psychometric properties, treatment utility, and conceptual basis of psychometric instruments used to identify the functions of aberrant behaviors in people with developmental disabilities. The instruments reviewed are the Motivational Assessment Scale (Durand & Crimmins, 1992), the Motivation Analysis Rating Scale (Weisheler, Hanson, Chamberlain, & Thompson, 1985), the Functional Analysis Interview Form (O'Neill, Horner, Albin, Storey, & Sprague, 1990), and the Functional Analysis Checklist (Van Houten & Rolider, 1991). Recurrent problems in this area include the lack of replicability of the reliability of these instruments, difficulties in summarizing the information from these assessment devices, difficulties in translating the assessment into treatment packages, strong individual differences in the functions of behavior problems, and, finally, issues relating to the concurrent validity, both across these instruments and across other assessment methods.