Purpose: This study aims to introduce the concept of communities of social media practice where more experienced users provide guidance to female novice users, enacting a form of legitimate peripheral participation to "onboard" newcomers. Design/methodology/approach: Through surveys with 968 early adolescents (average age was 13), the authors quantitatively explored sources and types of guidance for young social media users, popularity of conversation themes related to this guidance and how these conversations are associated with positive social media engagement. The authors qualitatively documented a case study of how a summer workshop of 17 students promotes positive social media use through a community of practice. Findings: Although early adolescent girls reported that they more frequently talked to their parents about a wider range of social media topics, same-age peers and younger family members (e.g., siblings, cousins) were also frequent sources. Surprisingly, the authors also found that the source most strongly associated with positive social media use was the peer group. This case study of an intentional community of practice demonstrated how peers go from "peripheral" to "centered" in socializing each other for more positive social media use. Originality/value: Unlike most prior scholarship on mediating social technology use, this study focuses on a critical developmental period (e.g. early adolescents), sources of guidance other than exclusively parents, explore the specific conversation topics that offer guidance and document an informal community of practice for girls that provides the training ground for peers and adult facilitators to codesign more positive social media spaces.