Prospective intergenerational mixed-methods investigation of the short- and long-term impact of COVID-19 on adolescent mental, social, and behavioral health - Abstract To better understand the short- and long-term impact of the COVID-19 pandemic on youth mental health and development, we will leverage our existing randomized controlled trial of a school-based healthy relationships program. In 2018, we randomized 24 Texas middle schools in disadvantaged communities in which students (n=2865; Mean age = 12.7; 50% female; 36% Black/African American, 26% Latinx; 14% Asian) received either standard health curriculum (n=12 control schools) or Fourth R (n=12 intervention schools). Participants completed baseline and three annual comprehensive follow-up assessments of their mental (e.g., depression, anxiety, hostility), social (e.g., living situation, socio-economic status, school climate, stress), and behavioral (e.g., dating violence, substance use, sexual behavior, (cyber)bullying, coping strategies) health. This longitudinal data, with relevant measures established prior to the COVID-19 pandemic and resulting stay-at- home orders, provides a powerful opportunity to understand the long-term impact of this global crisis on youth development, mental health, risk behaviors, and academic achievement and explore risk and protective factors moderating this impact. Thus, we will 1) administer an additional four years of annual follow-up surveys, beginning in the 12th grade and follow students until they are, on average, 21 years of age; 2) recruit and assess parents of participants; 3) augment our already extensive student-level data with comprehensive pandemic-related measures, as well as school-, neighborhood-, and environmental-level factors that may moderate impact; and 4) conduct qualitative interviews of educators (n=24), students (n=24), and parents (n=24) to obtain a richer understanding of factors that mitigated or exacerbated the impact of COVID-19 and resulting disruptions to school, family, mental health, and development. Specific aims are to 1) Determine the short- and long-term impact of the COVID-19 pandemic on adolescents' mental, behavioral, and social health, as well as their academic performance and career potential; 2) Examine the moderating impact of family and income stability, parent-child relationships, parent mental health, equity (access to education, digital divide), learning model (in-person, online, hybrid), school disruptions, and school and neighborhood climate on COVID- 19 impacts for youth; 3) Investigate whether and how pandemic-related stressors (individual/family COVID impacts of job interruption, food access, media consumption, and vaccine uptake) are linked to short- and long- term health behaviors and outcomes; and 4) Evaluate the secondary benefits of Fourth R in mitigating the negative impact of the COVID-19 pandemic. Given that the intervention targets mental wellbeing, conflict resolution, coping, and help-seeking, we hypothesize that students exposed to the intervention will evidence improved mental, social, and behavioral health relative to their counterparts in control schools. Our study will provide a rigorous and comprehensive understanding of the impact of COVID-19 – quantitatively by leveraging data from an ongoing cohort and contextually through qualitative investigation.