Specific disorders discussed include the antisocial personality, alcoholism, affective disorder, schizophrenia, and hyperkinesis. For each disorder, a definition and/or diagnostic criteria, clinical course, genetic aspects, the disorder's association with juvenile delinquency, and policy implications are discussed. For example, the antisocial personality has been defined as failure to conform to societal norms in diverse life areas, beginning prior to age 16. The commission of an antisocial act does not qualify an individual for this label, however. Relatively isolated antisocial behaviors can be seen in a variety of diagnoses. The syndrome begins in childhood or early adolescence and is characterized by a combination of such problems as pathological lying, lack of guilt, recklessness, sexual perversions, incorrigibility, staying out late, bad companions, and impulsiveness. Adults with antisocial personalities show effects of the syndrome in most areas of their lives. They also have a high rate of criminal recidivism and increased chances for an early death. The syndrome runs strongly in families and appears to be part of a genetically influenced spectrum of related disorders. The syndrome also shows strong links with juvenile delinquency. Limited data indicate that this syndrome responds in a limited way to authoritative, environmental control with the use of intense group pressures to produce conformity. However, these individuals' general resistance to change indicate that rehabilitation and treatment efforts aimed at juvenile offenders should be evaluated separately for those with antisocial personality labels and those without them. More research and carefully controlled intervention programs are needed in this area. It is concluded that the available data on the antisocial personality as well as the other syndromes show that each syndrome is theoretically connected with juvenile delinquency. Juvenile justice workers should learn the proper criteria and the expected natural history for these diagnoses, as well as the greater chances of juvenile problems among children from families with these problems. Proper treatments and referral mechanisms are also needed. Two tables and a list of about 125 rererences are provided.