Objective Suicide is a leading cause of death in adolescence. The mechanisms of adolescent suicidality, however, are not fully understood. Although the Interpersonal-Psychological Theory of Suicide, as assessed by the Interpersonal Needs Questionnaire-15 (INQ), may be a promising framework, systematic study of its utility during adolescence is lacking. Method To this end, we utilized factor analyses and hierarchical regression analyses to test the factor structure, correlates, and predictive validity of the INQ in a sample of clinically depressed and suicidal adolescents (N = 120, aged 12–18). The sample was mostly female (81.9%), ethnically diverse (68.2% non-White) and with nearly a third identifying as a sexual minority (31.8%). Results Contrary to studies including adult samples in which a two-factor solution is identified, results within this sample indicated three factors: perceived burdensomeness, thwarted belongingness, and perceived isolation. Perceived burdensomeness and the interaction between perceived burdensomeness and perceived isolation predicted suicide ideation above and beyond depression, but thwarted belongingness and perceived isolation did not. Conclusion Perceived burdensomeness appears to play a role in adolescent suicidality and may be a point of intervention, yet the notable deviation from previous findings and the relative weakness of two of the factors warrant further study.