PROJECT SUMMARY/ABSTRACT Parent Grant: Human Papillomavirus (HPV) incidence is disproportionally high among adolescents and young adults aged 15-24 years. The Centers for Disease Control and Prevention (CDC) recommends “catch- up” vaccination for young adults through 26 years. However, young adults, specifically college students, continue to display alarmingly low rates of HPV vaccination. The parent grant aims to develop and test a multilevel narrative-based intervention designed to address individual- and system-level factors to increase school-based vaccine access and HPV vaccine uptake among Texas college students. Proposed Diversity Supplement: This supplement will benefit the parent grant research by examining interpersonal influences on HPV vaccination decision-making that exist between the individual and system levels of influence as denoted in the parent grant and the Social Ecological Model. Importantly, parents and friends are often cited as the most influential people in vaccine decision-making among young adults. However, parents and friends can be perceived to express HPV vaccine disapproval, which can result in increased stigma surrounding the HPV vaccine. In this supplement, we will: (1) identify sociodemographic and psychosocial predictors of perceived HPV vaccine disapproval from family and friends (Aim 1); (2) examine how perceived HPV vaccine disapproval impacts both the behavioral skills needed to vaccinate against HPV and the stages of HPV vaccine decision-making (Aim 2); and (3) test the parent grant intervention’s ability to reduce perceived HPV vaccine disapproval from family and friends and, consequently, reduce HPV vaccination disapproval at follow-up (Aim 3). We will perform secondary data analysis using baseline and follow-up data from the parent grant. Block-sequential multivariate regression will be performed to determine sociodemographic and psychosocial predictors of HPV vaccine disapproval from parents and friends (Aim 1). Multinomial logistic regression will be used to test whether perceived HPV vaccine disapproval from family and friends is associated with an increased likelihood of being in the earlier stages of HPV vaccine decision-making. A path analysis will be performed to examine the impact of perceived disapproval from family and friends on HPV vaccination intentions through different behavioral skills (e.g., self-efficacy and information-seeking; Aim 2). Finally, both linear and logistic regression mediation analysis will be performed to examine whether the intervention is associated with decreases in perceived HPV vaccine disapproval from family and friends, which, in turn, decreases HPV vaccination disapproval at 3-month follow-up (Aim 3). Ultimately, this work will benefit the parent grant by identifying groups of college students who experience high levels of perceived vaccine disapproval/stigma from important others and, thus, are at high risk of being vaccine-hesitant and/or “stuck” in their HPV ...