NTA is the major drug treatment program in the District of Columbia, treating more than 17,000 people by the time of the study. The multimodal program used three strategies: methadone detoxification-abstinence, methadone maintenance, and drug-free programing that included individual and group counseling and regular urinalysis. The study used data from a random sample of persons over age 17 who had entered the program during 1970-73. One-third had spent at least half their time in the methadone maintenance program; one-third had spent at least half their time in detoxification-abstinence; and one-third had left in the first 5 days. Ninety-five percent of the persons were located and interviewed 1 to 3 years after treatment. Results indicated that treatment had no impact on outcomes. Winick's "maturing out" hypothesis may explain these results. However, more likely explanations are that factors outside the treatment process produced behavior change, that the decision to seek treatment represented a commitment to change, or that law enforcement efforts made it more difficult for heroin addicts to obtain drugs. Further research is recommended. Tables and 7 references