Background: Maladaptive emotion regulation strategies are predictive of negative outcomes in adolescence which, in turn, may impact on later well-being. Objective: The current study aimed at testing the moderating role of emotional self-efficacy on the relation between expressive suppression and the engagement in internalizing behavior, controlling for gender effect. Method: A total of 526 adolescents (M[subscript age] = 14.7 years, age range = 14-17 years) filled out self-report questionnaires evaluating expressive suppression, emotional regulatory self-efficacy, and internalizing behavior, respectively. Results: Suppressors with lower positive emotion self-efficacy were more likely to engage in internalizing behavior than suppressors with higher positive emotion self-efficacy. Conclusions: Despite several limitations, the study provided preliminary insights on the role played by emotional self-efficacy in the relation between expressive suppression and internalizing behavior in middle adolescence.