Study determined the change in prevalence of Methylphenidate misuse over the last four years in adolescents (N=240) assessed at an outpatient abuse treatment facility. Results showed a significant increase in Methylphenidate misuse over the last 2.5 years; this increase was greatest in White adolescents. Suggests that treatment with Methylphenidate in adolescents at risk for substance misuse should be considered carefully. (Author/MKA)