In most such studies, multivariate statistical techniques have been used to examine overt behaviors, attitudes, personality characteristics, and values in samples of institutionalized or adjudicated delinquents. In general, such studies have identified four major delinquent subgroups or types. The undersocialized aggressive type is assaultive, disobedient, destructive, untrustworthy, and boisterous. The socialized aggressive type is often truant, has delinquent peers, stays out late at night, and often is involved in group theft. The attention deficit subgroup is characterized by preoccupation, a shorter attention span, and impulsivity. The anxious-withdrawn-dysphoric type is usually depressed, anxious, shy, hypersensitive, and socially withdrawn. Differences among these types have been found in institutional adjustment, recidivism, instrumental learning, peer relations, and psychophysiological responsiveness. In general, the prognosis is worst for the undersocialized aggressive subgroup. 72 references.