Research suggests that growth mindset shows positive effects on adolescents' academic achievement, especially in overcoming academic-related setbacks. It remains unclear, however, how growth mindset functions in the presence of social stress, a risk factor for adolescent mental health. In the present study, we explored how growth mindset of thoughts-emotions-behaviors predicted dual indicators of adolescents' mental health (life satisfaction and emotional problems), and if and how growth mindset interacted with peer and family stress to predict mental health. A total of 791 adolescents (Mage = 16.32 years, SD = 1.1, range 14-18; 60.8% female; 9th-12th grades; African American 34.5%, White 31.4%, Asian 13.2%, Hispanic 11.6%, biracial or multiracial 8.2%, others 1%, and missing 1%) participated via self-report surveys. A structural equation modeling approach was adopted to simultaneously model both the main and interaction effects. Results showed one significant interaction effect-between growth mindset and peer stress-on predicting life satisfaction (β = 0.13) and a significant main effect of growth mindset on predicting emotional problems (β = -0.35). The main effects of family stress on both outcomes (β = -0.22, life satisfaction; β = 0.18, emotional problems) were significant in the expected directions. Thus, growth mindset is a contributing factor to better mental health (higher life satisfaction, fewer emotional problems) and a buffering factor that mitigates the negative impact of peer stress on life satisfaction. These findings enhance the understanding of growth mindset, which can be integrated into school psychologists' work to assess or promote adolescent mental health. (PsycInfo Database Record (c) 2023 APA, all rights reserved).