The research collected information through personal, semi-structured interviews, usually in the participants' homes, and tracked the participants for 3-10 months to monitor changes in health, drug use, and social factors. The analysis focused largely on the 18 participants who attended only once; the longitudinal analysis focused on the 9 participants who were matched and who completed all 3 interviews. Those who left treatment were likely to be younger, on probation, using more recreational drugs, and with parents who were aware of their attendance at a drug treatment program. Analyses of the changes in amphetamine use over time revealed an initial decline in the frequency and amount of amphetamine used for the early leavers, similar to that of amphetamine users who continued in treatment. This reduction did not continue in the second month, although it became more pronounced for those still receiving treatment. Findings suggested that the high degree of motivation required by amphetamine users to seek help from a drug treatment service provides a strong incentive for preliminary behavior change even without continued treatment and that support and guidance of skilled drug workers assist the sustained reduction in amphetamine use. Tables and 13 references (Author abstract modified)