This two-year study evaluates a mobile phone-based comprehensive sexuality education program designed to support adolescent sexual and reproductive health in Kenya, where rates of teenage pregnancy and sexually transmitted infections remain high. The program, called AskDoki, delivers age-appropriate health information through the WhatsApp platform and is supported by trained youth peer leaders known as Digital Champions, who help adolescents access and use the program. Communities participating in the study are assigned either to receive the AskDoki program with Digital Champion support (intervention communities) or to not receive the program (comparison communities). Adolescents in both intervention and comparison communities complete surveys before the program begins and again six months after implementation of the AskDoki program. The surveys assess health knowledge, attitudes, perceptions, and intended behaviors related to sexual and reproductive health. The study compares changes in survey responses over time between intervention and comparison communities to assess the program's effectiveness. It also evaluates how feasible it is to use Digital Champions to support adolescents' engagement with the mobile program and examines the cost-effectiveness of this approach.