This longitudinal study investigates whether there are particularly salient ages when being overweight is related to problems in interpersonal relationships (i.e., physical, relational, and verbal victimization, lack of friend social support, dating status, and romantic relationship worries). Participants were from a large, six-wave longitudinal study (N = 662, 48% males, M age at T1 = 15.5 years, SD = 1.9 years). We use time-varying effect models to estimate how the associations between weight status and interpersonal problems differ from ages 12 to 28. Gender differences are also investigated. Findings show that youth who are overweight are more likely to experience verbal victimization, feel less supported by their peers, and are less likely to date than youth who are not overweight from mid-adolescence into early young adulthood. Further, females who are overweight are more likely to be physically victimized at ages 15 to 22 than females who are not overweight. The results provide a better understanding of age-related changes in interpersonal problems among youth who are overweight from adolescence into young adulthood.