The heterogeneity of experiences among adolescents in the digital age is often characterized by overgeneralized negative narratives regarding ubiquitous social technology use. There is limited research and practice surrounding a person-centered approach that may uncover differential impacts to development and mental health. Furthermore, as adopters of online spaces become younger, little is known about the critical transition period between childhood to adolescence, which can influence developmental trajectories in the digital age. This dissertation takes an overarching multimethod and social ecological perspective (i.e., individual, interpersonal, institutional and macrosystem) to explore early through later adolescent development and wellbeing coupled with their use of social technologies. Chapter 1 takes an individual person-centered analytic approach to investigate associations between early adolescent growth trajectories of psychosocial indicators and increased social media use across 4-years of this developmental period. This study leveraged a national sample of 6251 early adolescents (ages 9-13) in the US from the larger ABCD Study®. Results showed substantive growth of social media use and evidence of co-development with externalizing symptoms and prosocial behaviors. Girls were more likely to increase in internalizing symptoms over time, while boys decreased over this period of development. Exploratory analyses also showed differential patterns of growth across this sample of early adolescents when patterns were examined separately by racial-ethnic and family income indicators. Chapter 2 investigated interpersonal dynamics through daily measures of social belonging (i.e., with family and peers) and its links to various daily social technology engagements (i.e., communication, entertainment, content creation) over the course of a 14-day ecological momentary assessment of 388 adolescents (ages 10-17). Results showed that on days that adolescents reported greater peer social belonging they were also more likely to engage in increased use of social technology for entertainment purposes. Furthermore, adolescents who reported more psychological distress at baseline exhibited a stronger daily coupling of heightened feelings of family belonging and decreased social technology use for communication. Lastly, Chapter 3 presents a qualitative evaluation of an intergenerational Youth Advisory Board (YAB; ages 12-24) case study grounded in a positive youth development framework. This was implemented for the re-development of a co-design summer Digital Wellbeing Workshop curriculum tailored to diverse groups of middle school girls. This process evaluation showcased institutional and macrosystem level strengths and opportunities for integrating youth voices in the research and design practices for the development of digital tools that support middle school girls. The implications of the findings for each of the studies are discussed throughout the dissertation.

Adolescents’ rising depressive and anxiety symptoms paired with near constant use of mobile technologies, and more recently social media, has triggered concerns around this relation and synchronous trend. Yet, evidence has been limited to warrant causal effects and most prior research has examined these factors in isolation. Given that multiple factors are likely to determine both adolescents’ mental health and how they interface with technology ecosystems, there is a need for a broader understanding of how the interactions influence outcomes during this developmental period. This study utilizes data from a recent national sample of early adolescents (N = 11,875) to examine multilevel correlates of internalizing behaviors through the lens of the digital age. Analyses and interpretations are framed around a Social Ecological Framework (SEF) to evaluate and compare associations of factors across the tiered domains of the framework. These include individual factors (e.g. screen time, cognitive functioning), family factors (e.g. family conflict and parental monitoring), social factors (e.g. peer relationships), and community-level factors (e.g. neighborhood safety). Results indicate small positive associations between screen time and internalizing problem behaviors among early adolescents, yet social ecological factors such as family conflict, and neighborhood safety yielding stronger associations with internalizing behaviors. Adolescent sex and racial/ethnic difference also pose an important role in the association between screen time and mental health. The findings suggest that multiple social ecological factors beyond technology use may influence internalizing behaviors to a greater extent during early adolescence.