The study found that dynamic client characteristics - rather than fixed demographic, mental health, and drug-use characteristics - were associated with retention in treatment. These dynamic characteristics included motivation to attend treatment, expectations about treatment outcomes, positive experiences with treatment staff, and feeling involved in the treatment process. These findings support previous research, which has found that staff attitudes and client ability to bond with other youth in treatment significantly impact treatment retention. These findings suggest that treatment staff must be trained in the cultivation of positive group dynamics, staff-client interactions, and the solicitation of youth input and active involvement in the treatment regimen. The median length of stay in treatment was 2.7 months for the 42 youth attending day/residential services and 4 sessions for the 37 youth attending outpatient services. Of those participating in day/residential services, 16.7 percent dropped out of treatment early (within the first month), and 32.4 percent of participants in outpatient treatment services dropped out of treatment early (before the third session). Data were collected from structured interviews with the 79 youth, who were recruited from a clinical file search of 184 randomly selected youth who had attended youth-specific AOD services in Aotearoa, New Zealand during 2003 or 2004. 2 tables and 21 references