The investigators will conduct a stratified, randomized cluster trial of 20 diverse primary care practices to compare influenza vaccination rates in intervention and control sites. Intervention sites will use a package of newly developed and evidence-based techniques that will be tailored to their practice structure and culture, called the 4 Pillars Immunization Toolkit, in addition to receiving donated vaccine for early season vaccination. Control practices will not receive such assistance but will receive the intervention in the second year.
