Abstract: Relational health, a termed coined by Liang et al. (2001) to reflect Relational-Cultural Theory concepts, is the presence of growth-fostering characteristics in significant relationships. Although growth-fostering relationships have been conceptualized as relevant across the lifespan, existing research has mainly explored the experiences of college students and adults. In this study, the authors seek to create a developmentally appropriate instrument called the Relational Health Indices for Youth (RHI-Y) for studying growth-fostering relationships among early and mid-adolescents. This measure adapts the original adult RHI instrument for a younger population (i.e., utilizing a simpler vocabulary and containing fewer items). Measurement development resulted in six-item scales assessing relational health in three different relationship domains: friendships, relationships with an adult mentor, and relationships with members of a community group. Results indicate that the RHI-Y scales are valid, reliable measures of growth-fostering relationships. Preliminary findings about the correlates of relational health in youth are discussed.