Maintaining study cohorts over time is crucial to the success of treatment outcome research studies. This paper examines reasons why adolescents with substance use problems continued to participate in follow-up interviews. The sample consisted of 145 adolescents between the ages of 12 and 18, who completed an outcome study following out-patient treatment for substance use. Adolescents' top reason for continued participation was financial compensation; however, a high percentage of adolescents responded favorably to several other attitudinal questions concerning their follow-up participation, suggesting that the adolescents had a primarily positive view of their research experience and that reasons for research participation are multidimensional.