#4Corners4Health: A Social Media Cancer Prevention Program for Rural Emerging Adults - Several risk factors are prevalent during early adulthood that can lead to chronic disease and cancer later in life. Emerging adults (EAs) aged 18-26 residing in rural areas of the United States engage in many cancer risk behaviors, especially sedentary lifestyles, poor eating patterns, nicotine product use, excess alcohol intake, infrequent sun protection, and decisions not to practice prevention for human papillomavirus. This application responds to RFA-CA-20-051, “Social and Behavioral Intervention Research to Address Modifiable Risk Factors for Cancer in Rural Populations.” The goal is to improve cancer risk behavioral factors among a sample of individual EAs aged 18-26 living in rural counties in the western United States, using a health education intervention delivered online and designed with community advisors. EAs, including in rural communities, are heavy consumers of online content, and technology mediated communication platforms provide responsive, engaging, and low-cost platforms for distributing cancer prevention information with high dissemination potential. The specific aims of this research are to: 1) Develop a health education intervention for individual EAs living in rural communities via a community-engaged process that combines expert advice, user- generated content, and online information about behavioral cancer risks and family communication; 2) evaluate the effect of a theory-based online health education intervention on moderate to vigorous physical activity (MVPA), healthy eating patterns, nicotine product use, alcohol intake, sunburn prevalence, and the prevention of human papillomavirus infections and related cancers among a sample of individual EAs aged 18-26 living in rural counties in the western United States recruited from online survey panels and online advertising and enrolled in a pragmatic randomized trial using a stepped-wedge design in which individual EAs will be randomized to 1 of 4 cohorts and receive the intervention for varying durations in separate Facebook private groups; 3) test if improvements in individual EAs’ cancer risk knowledge and family communication are related to effects of the online health education intervention; and 4) explore whether the effects of the online health education intervention differs according to: a) level of EAs’ engagement with the intervention, b) cancer risk factors, and c) biological sex of the participants (male v. female). The research is innovative because it tests a theory-based, multi-risk factor approach to cancer prevention education with a sample of individual EAs living in rural counties using a very popular new media. Technology-mediated interventions may reach individual EAs more than interventions through other community channels (e.g., clinics, schools, and workplaces) and for lower cost in the geographically dispersed, rural communities in the western United States. The overall impact is extremely high because it will aid rural EAs in making informed decisions that reduce cancer risk factors and prevent chronic disease and cancer later in life.