A prospective study was made of 200 consecutive children to evaluate the usefulness in the diagnosis of infantile autism of the behavioral scale reported by Clancy and coworkers in 1969. On this scale seven or more of 14 behavioral manifestations must be present before a diagnosis of autism can be made. Using this scale alone, 48 of the 200 children studied were "scale positive", i.e. could be considered autistic. However, further study of this group showed that only one child fulfilled the classical criteria of Kanner (1943) for a diagnosis of early infantile autism. Scale "positivity" was found to correlate with mental retardation and to be associated with other developmental defects, especially learning disorders and hearing loss.