Callous–unemotional (CU) traits designate a unique subset of youth with externalizing psychopathology who have a severe pattern of aggressive behavior and tend to have worse outcomes in treatment. However, little research has addressed how CU traits relate to different components of psychotherapy, such as the therapeutic alliance. The current study examined the role of CU traits in predicting therapeutic alliance in 59 adolescents (M age = 15.3, 51% female, 64% Hispanic American, 15% African American) who were part of a larger randomized naturalistic trial of outpatient behavioral psychotherapy. Multilevel regression analysis further investigated the role of therapeutic alliance in predicting treatment outcome (as measured by self-reported delinquency) and the moderating role of CU traits. Results suggested that regardless of the severity of their externalizing problems, youth with higher levels of CU traits reported more positive ratings of therapeutic alliance. In addition, a positive therapeutic alliance predicted reductions in delinquent behavior, and this association was even stronger for youth higher in CU traits. Our results suggest that CU traits are related to improvement in the formation of the therapeutic alliance among youth with externalizing psychopathology, perhaps because these youth lack many of the social and emotional deficits that other youth with conduct problems possess. Adolescents high in CU traits should not be viewed as untreatable. Indeed, the therapeutic alliance may be an important mechanism for affecting meaningful change in these adolescents’ lives.