A questionnaire (the Wing Subgroups Questionnaire, or WSQ) for subclassifying children with autism into one of Wing's three hypothesized subgroups was developed, and the validity of this measure was assessed. Forty parents of children with autism or pervasive developmental disorder not otherwise specified (PDDNOS) completed the questionnaire. Results indicated that the questionnaire has adequate external criterion-referenced validity with similar subgroup ratings made by clinicians, and good internal consistency. Furthermore, results revealed three distinct and separate subgroups corresponding to Wing's subclassification scheme. Other analyses suggested that Wing assignment based on the WSQ was independent of chronological age and age equivalents for social and daily living skills, but not independent of diagnosis of autism vs. PDDNOS, IQ, severity of autism, sex, receptive language mental age, and age equivalents for communication skills. Finally, a discriminant analysis indicated that, of all the dependent variables examined in the present study, the clinicians' Wing assignment was the best predictor of Wing assignment based on the parent-completed WSQ. These findings provide support for Wing's classification system, and suggest that the WSQ is a valid and useful tool for subclassifying individuals with autism.