Annual influenza epidemics result in substantial mortality and morbidity among adults and children with more than $10 billion in direct medical costs. Although national guidelines recommend annual influenza vaccination of all school-aged children, less than half of these children are vaccinated. The major barrier is the short time window for vaccination: primary care practices are simply unable to vaccinate all of their pediatric patients within a few months. An alternative setting for child influenza vaccination is school-located influenza vaccinations (SLIV), yet <5% of children receive vaccine in schools. Three barriers impede SLIV: an ineffective paper-based parent consent system, ineffective parent reminders, and lack of experience with SLIV among adolescents. The goal of this project is to address these 3 barriers and to optimize influenza vaccination rates via SLIV. We will adapt two dissemination/implementation conceptual models (the Chronic Care Model and RE- AIM). We will work closely with schools, primary care practices, and local and state public health leaders, and with two national partners - CDC's National Center for Immunization and Respiratory Diseases (NCIRD) and the National Association of School Nurses (NASN). We propose a technical aim, a scientific aim, and a dissemination aim. The technical aim (Aim 1, Yr 1) is to develop, pilot, and evaluate a web-based consent and parent reminder system, using an innovative web-based informatics system. We will perform formative studies of parents, school staff, and providers, to create a useful system. The scientific aim (Aim 2, Yrs 2-4) is to perform effectiveness testing of SLIV, using web-based consent + reminders. We will randomize schools to SLIV vs. control in 3 successive annual RCTs, with increasing number of schools, and measure vaccination rates, school absences, and SLIV processes and costs. In Yr 2 we will include 5 schools districts (all elementary; 26 study, 28 control schools, n=25,078). In Yr 3 we will expand to 8 school districts and also middle/high schools (n=59,556 children); in Year 4 to 12 districts (n=79,713 children). The dissemination aim (Aim 3, Yrs 4-5) is to spread SLIV throughout Monroe County and diffuse SLIV best practices and technological innovations nationally. We will offer SLIV to all county schools (182 schools, n=112,034), and work with national partners to disseminate the consent/reminder system and a training program for SLIV across the US. This project addresses AHRQ priority area Prevention/Care Management, includes a focus on priority populations (adolescents, urban), and is a major redesign of primary care.