 The uptake of vaccines for Human Papillomavirus HPV in the U.S. is far below recommended levels, particularly for adolescent boys and especially among minority families. Proposed here is a mobile web application mobile web app for personal computers, smart phones, and tablet computers that will accurately inform parents and adolescent boys about the HPV vaccination and address unique concerns about its safety and effectiveness for boys. The BoyVac mobile web app will be evaluated for its ability to improve vaccine outcomes in a randomized efficacy trial with parents and adolescent boys aged 11-13 years who obtain care in pediatric clinics in the University of New Mexico Health Sciences Centers Envision network. 