Abstract
This study examines links between self-disclosure and relationship quality with close friends from adolescence to adulthood. A diverse community sample of adolescents (N = 184) participated in survey and observational measures annually from ages 13 through 29, along with their close friends and romantic partners. Random intercept cross-lagged panel modeling (RICLPM) was used to parse markers of within-individual change from age 13 to 18. Long-term longitudinal path models also investigated cascading associations among self-disclosure and relationship quality, on aggregate, from adolescence to adulthood. Adolescents who reported a higher-quality friendship in a given year demonstrated greater-than-expected increases in self-disclosure the following year, and an adolescent demonstrated high self-disclosure one year reported greater-than-expected increases in friendship quality the following year. Higher mean self-disclosure in adolescence predicted higher mean self-disclosure in adulthood. Results are interpreted as identifying high-quality adolescent friendships as key contexts for developing intimacy-building capacities (i.e. self-disclosure), which sets the stage for satisfying close relationships in adulthood.