This study uses a structured vignette procedure to assess competency to make treatment decisions in two groups of adolescents, one at risk for institutional placement and the other a matched community sample. Scores on Factual Understanding (the ability to recall facts), Inferential Understanding (the ability to make inferences about those facts), and Reasoning (the ability to weigh risks and benefits of various treatment options and to make choices based on that reasoning) were compared. Results showed that while at-risk adolescents and their community counterparts did not differ in their factual and inferential understanding abilities, the at-risk adolescents did significantly less well than the community adolescents in reasoning. This difference couM not be fully explained by differences in verbal 1Q. Girls, no matter what their risk status, scored higher than boys on the Reasoning scale. Implications for legal policies concerning adolescents are discussed.How much adolescents should be involved in decision making about mental health treatment is a controversial policy question, Historically, parents or the state have been entrusted to see that adolescents received care when it was in their best interest (Parham v. J.R., 1979;Melton, 1984). Recently, however, many have questioned this general framework (e.g., Melton, 1989). A call to expand adolescents' autonomy under the law has arisen, especially regarding their rights to make decisions about their own medical care (Interdivisional Committee on Adolescent Abortion, 1987; Gittler, Quigley-Rick, & Saks, 1990).The empirical support for this position rests primarily on a set of studies that compared how adolescents and adults make decisions about hypothetical treatment situations. These studies have generally demonstrated no difference in the outcomes chosen and the logic used by adults and adolescents above the age of 14 (e.g.,
