The purpose of this study is to find out more about how to provide effective further treatment for adolescents who have received six weeks of group therapy for substance-use problems and continue to use drugs. Treatments used in the study include a group therapy (MET/CBT), an individual therapy (CBT), and a family therapy (FFT). The study will look at whether abstinence or a very low level of use is a better guide for deciding whether further treatment is needed, how well different combinations of treatment work to reduce substance use, and whether it is possible to predict in advance which adolescents will respond best to which types of treatment. Study investigators expect that a treatment strategy using what is learned about these issues in the first half of the project to develop an "adaptive" treatment model will work better than a "fixed" treatment to reduce adolescent substance use.