Reviews and critiques relevance of Diagnostic and Statistical Manual of Mental Disorders, Third Edition-Revised (DSM-III-R) for school psychological practice. Presents five misguided assumptions upon which DSM-III-R use is based, dealing with medical model conceptualization of behavior; reliability; validity; relevance for special education placement; and treatment validity. Concludes that DSM-III-R is largely irrelevant for school psychology practice. (Author/NB)