Using latent class/transition analyses, this study: (a) identified subgroups of youth based on their targeted communication about substance use with parents and friends, (b) examined subgroup differences in substance use, and (c) considered changes in subgroup membership over four years. Among 5,874 youth, five subgroups emerged, with parents-only communicators having the lowest substance use. Friends-only and consequence-focused communicators reported the overall highest use. Subgroup membership was mostly stable across the four years. If, however, youth transitioned, those who began as parents-only, consequence-focused, or friends-only communicators during the first year were most likely to transition to comprehensive communicators by the last year. Youth who started as noncommunicators or comprehensive communicators were most likely to end up as parents-only communicators.