The correlation of ratings from the SNAP Rating Scale with the ratings from the established Conners' Ratinq Scale are discussed as a method for assessing the validity of the new Diagnostic and Statistical Manual of Mental Disorders (DSM-III) criteria for attention deficient disorder with hyper-activity (ADDH). The questionnaire of SNAP items and Conners' items completed by teachers of six to eleven-year-old students in Toronto, Ontario and Tallahassee, Florida is discussed. The average score per item in subcategories of inattention, impulsivity, and hyperactivity is shown to decline with age and is higher at each age for boys. Concurrent validity of the SNAP rating scale is established by the high correlation with Conners' rating scale. Study data is detailed in statistical tables. Norms presented in the study are shown to be useful for initial assessment of attention deficient behavior in the classroom related to the diagnosis of ADDH. A SNAP item list and Conners questionnaire are provided. (Author/CM)