Objective: When psychotherapy is brief (1-2 sessions), “early dropout”—defined as premature treatment discontinuation due to financial or structural barriers—is a commonly-assumed cause. However, there are several possible reasons why treatment may be brief, including youth-level factors such as psychopathology complexity or problem type. Better characterizing whether factors beyond financial and structural barriers predict adolescents’ receipt of briefer treatment may guide efforts to retain specific youth in services—and disseminate intentionally-brief interventions to youth positioned to benefit.Method: Using data from the 2017 SAMHSA National Survey on Drug Use and Health, we examined whether sociodemographic disadvantage (minority race, low-income, government assistance), perceived problem type, and psychopathology complexity (1 versus multiple problem types) related to psychotherapy length (1-2 versus 3-24+ sessions) among adolescents receiving outpatient psychotherapy (N=1,601; ages 12-17; 60.59% white; 64.50% female). Results: Among adolescents beginning outpatient psychotherapy, 23.36% ended treatment after 1-2 sessions. Psychopathology complexity predicted greater likelihood of receiving >2 sessions, after adjusting for specific problem type (χ²=75.14, p<.001, OR=1.80). Further, although certain problem types (depression; anxiety; anger control) were associated with increased likelihood of greater treatment length, these findings did not hold after accounting for psychopathology complexity. No sociodemographic factors significantly predicted treatment length. Conclusions: Structural and financial barriers alone may not explain when and why youth psychotherapy is brief. Psychopathology complexity may be a meaningful contributor to youth treatment duration. Future research may test whether youth with less comorbidity differentially benefit from intentionally-brief interventions, along with targeted strategies for preventing dropout among youth requiring longer-term services.