--- - |2 Abstract The purpose of this mixed methods study was to examine the relationship between attachment, supportive nonparental youth‐adult relationships, and self‐esteem during adolescence. First, in a quantitative path analysis, we found that perceived social support from nonparental adults partially mediated the relationship between adolescent attachment and self‐esteem. In our follow‐up mixed methods analysis, we analyzed youth reflections of support experienced in relationships with significant non‐parental adults (VIPs). As compared to youth with positive attachment models, youth with negative attachment models reported fewer instances of emotional support but more instances of validation support. The youth with negative attachment models described (1) the importance of trust and (2) receiving emotional support specific to their needs. In instances of validation support, these youth described how their VIPs (1) provided them with honest and realistic feedback, (2) challenged their negative thinking and (3) created opportunities for them to recognize and showcase their strengths. Our findings underscore the importance of considering youths' individual attributes in the context of their ongoing relationships in order to gain a more nuanced understanding of the role and dynamics of supportive nonparental youth‐adult relationships in youths' lives. - Journal of Community Psychology, EarlyView.