Adolescents' dyadic relationships are likely influenced by the cultural context within which they exist. This study applied a person-oriented approach to examine how perceived support and negativity were manifested across youths' relationships with mothers, fathers, and best friends, simultaneously, and how distinct relationship profiles were linked to adaptive and maladaptive functioning (aggression, anxious-withdrawal, prosociality) within and across cultures. Participants resided in metropolitan areas of South Korea, the United States, and Portugal (10-14 years; N = 1,233). Latent profile analyses identified relationship profiles that were culturally common or specific. Additional findings highlighted commonality in the relations between a high-quality relationship profile and adaptive functioning, as well as cultural specificity in the buffering and differential effects of distinct relationship profiles on social-behavioral outcomes.Close interpersonal relationships have long been recognized as significant developmental contexts for youth. For example, parent-child relationships are presumed to be the primary sources of social support throughout childhood and during the transition to early adolescence (10-14 years; Collins & Laursen, 2013). However, friendships become increasingly salient and influential as the amount of time spent with friends grows and as friendships become more intimate (Rubin, Bukowski, & Bowker, 2015). Despite the well-documented contributions of parents and friends to a wide range of youths' social-behavioral outcomes (e.g., prosociality and aggression), defining the nature and structure of these relationships and their unique functions during early adolescence has been challenging. This is, in part, because specifically identified close relationships can have an impact on developmental outcomes, while at the same time,