Within a population of children referred for school-related problems, youngsters with significant attention deficits were compared with children having other types of learning problems. Using data from parent and teacher questionnaires as well as results of multidisciplinary team assessments, each patient was assigned either to a group with significant attention deficits or to one with learning problems, but fewer, if any, problems with attention. Disagreement between observation sources was demonstrated. Children qualifying for the significant attention deficit group were characterized by a greater likelihood of having behavioral problems during the toddler and preschool years. They also had a higher prevalence of minor neurologic signs and difficulty on tests of language development. Their current behavioral and adjustment problems seemed to be more severe and widespread than those of the youngsters with whom they were compared. No major intergroup differences were observed with regard to age at referral, socioeconomic status, family history of learning and behavior problems, perinatal health risks, or psychosocial difficulties. There was considerable historic and symptomatic overlap between the two groups, suggesting that the clinical picture characteristic of significant attention deficits is relatively nonspecific and is either a primary or secondary finding in a large proportion of a heterogeneous population of children experiencing difficulties in school.