Trained interviewers utilized a structured research instrument to analyze drug use patterns, personal and familial psychiatric problems, and social backgrounds of a consecutive series of 355 adolescent referred by courts to alcohol counselling and education centers in King County. Within this sample, 4% of the subjects used propoxyphene alone, 16% reported use of phencyclidine (PCP) alone, and 6% reported abuse of both substances. The data consistently reveals that the use of one of these more unusual substances is likely to occur in people with more antisocial, drug, and alcohol problems. Use of both drugs was associated with the most pervasive antisocial history, with over one-third of these subjects fulfilling strict criteria for the antisocial personality. The treatment and prognostic implications of these findings are discussed.