This study investigated baseline client characteristics that predicted long-term treatment outcomes among adolescents referred from school and community sources and enrolled in usual care for conduct and substance use problems. Predictor effects for multiple demographic (age, sex, race/ethnicity), clinical (baseline symptom severity, comorbidity, family discord), and developmental psychopathology (behavioral dysregulation, depression, peer delinquency) characteristics were examined. Participants were 205 adolescents (52 % male; mean age 15.7 years) from diverse backgrounds (59 % Hispanic American, 21 % African American, 15 % multiracial, 6 % other) residing in a large inner-city area. As expected, characteristics from all three predictor categories were related to various aspects of change in externalizing problems, delinquent acts, and substance use at one-year follow-up. The strongest predictive effect was found for baseline symptom severity: Youth with greater severity showed greater clinical gains. Higher levels of co-occurring developmental psychopathology characteristics likewise predicted better outcomes. Exploratory analyses showed that change over time in developmental psychopathology characteristics (peer delinquency, depression) was related to change in delinquent acts and substance use. Implications for serving multiproblem adolescents and tailoring treatment plans in routine care are discussed.