Objective: This study examines the psychometric strength, including cross-ethnic validity, of two subscales of Muris' Self-Efficacy Questionnaire for Children: Academic Self-Efficacy (ASE) and Social Self-Efficacy (SSE). Methods: A large ethnically diverse sample of 3,358 early and late adolescents completed surveys including the ASE and SSE. Analyses focused on the subscales' psychometric properties for the aggregate sample as well as for specific racial/ethnic subgroups. Results: For the ASE, Cronbach's a for the aggregate sample is 0.85, ranging from 0.84 to 0.86 across racial/ethnic subgroups. For the SSE, the aggregate Cronbach's a is 0.81, ranging from 0.77 to 0.86 across these subgroups. Conclusions: While aggregate findings indicate psychometric strength, analyses of cross-ethnic validity find some factor structure and item loading differences across racial/ethnic subgroups, indicating the need to ensure accurate measurement of self-efficacy across diverse youth samples.