Modified Project Summary/Abstract Section - Project 3 8537 The development of socioemotional well-being in adolescence is crucial for mental and physical health. Technology and digital media (TDM), and especially social media, are highly used among adolescents and hold risks and opportunities for socioemotional well-being. The long-term goal of our research is to promote well-being for adolescents and young adults by decreasing negative social media activities and amplifying positive social media activities. The objective of this Project is to understand the types of social media content that adolescents create (self-generated) and consume (other-generated), and how these social media activities affect socioemotional well-being. The Aims are: 1) To test bidirectional relationships between self-generated TDM content and socioemotional well-being; and 2) To test bidirectional relationships between other-generated TDM content and socioemotional well-being. The PI, Co-Is, and Consultant on this Project bring decades of research experience with adolescents and social media. The PI’s preliminary work has included development of a novel ethnographic approach to directly observed self-generated social media content and accumulated experience with longitudinal study design in early adolescents. The proposed Project will use longitudinal data collection over 2 years. The shared participant pool for this P01 program will be leveraged to recruit the sample of 400 adolescents aged 13-15 years at enrollment. Data collection approaches included online ethnographic observation of participants’ self-generated social media content, thematic analysis of other-generated content experienced by participants, individual interviews, and survey administration. These data will be used to test a cross-lagged panel model examining socioemotional well-being as a predictor and outcome of self-generated and other-generated social media experiences over time. This Project aligns with the current RFA as it tests how TDM usage impacts social-emotional development and health outcomes in adolescents.