The aim of this research was to explore whether perceived support from classmates moderates the relationship between core self-evaluations (CSE) and psychological well-being indicators among adolescents. The Core Self-Evaluations Scale, the Teacher and Classmate Support Scale, the Satisfaction with Life Scale, the Frequency of Suicidal Ideation Inventory, and the Depression, Anxiety, and Stress scales were administered to 2,883 Spanish adolescents (Mage = 14.07). Perceived classmate support moderated the relationship between CSE and life satisfaction, depressive symptoms, and suicidal ideation. These findings provide empirical support for theoretical and conceptual work connecting perceived classmate support, CSE, and psychological well-being among adolescents, suggesting that alone, but also in combination, these personal and social resources may be particularly relevant in helping to promote psychological well-being. Theoretical and practical implications of the joint study of these constructs and their relationship with psychological well-being in adolescents are discussed.