IntroductionExperiencing elevated stress increases the risk of further difficulties in mental health, including externalizing behaviors in adolescents. There is a need for understanding the factors that help adolescents mitigate social stress to prevent problematic externalizing behaviors. Growth mindset has been found to be a promising protective factor in adolescent development including mental health. This study aimed to examine the potential buffering role of growth mindset of thoughts‐emotion‐and‐behaviors in the context of two types of social stress (i.e., family and peer) to reduce externalizing behaviors among adolescents.MethodsThe sample is composed of 399 adolescents (age range 14–18 years, M = 16.22, SD = 1.21; 56.4% female, 42.3% male, 1.3% gender‐nonconforming or variant) from a large, urban, diverse high school in the United States. Adolescent self‐reports were administered at one time.ResultsModeration analyses revealed that growth mindset of thoughts, emotion, and behaviors moderate the association between family stress and externalizing behaviors. The magnitude of this association weakened as the level of growth mindset increased, supporting the buffering effect of the moderator. Neither the moderation effect of growth mindset nor the main effects of peer stress and growth mindset were significant in predicting externalizing behaviors.ConclusionTaken together, the findings suggested that growth mindset has protective effects in reducing externalizing behaviors when adolescents experience family stress. Future directions and implications are discussed.