OBJECTIVE: The American College of Physicians (ACP) developed a quality improvement (QI) program to address deficiencies in immunization rates, primarily for influenza, and determine the program's impact on adult immunization. DESIGN: An interventional study using a pre-post design. Three cohorts of physician practices were invited from a random sample of 2000 to attend 1-day training sessions in 2004, 2005, and 2006 in Philadelphia, Pennsylvania. Participants performed data abstractions and developed QI plans. Baseline data were compared with follow-up. RESULTS: Fifty-five practices received training, 39 practices provided baseline data, and 11 practices provided follow-up data, reporting on 4208 patients. Baseline rates for influenza were 51% for cohort 1, 42% for cohort 2, and 59% for cohort 3. Follow-up data collection is ongoing. CONCLUSION: Rates increased for patients with private insurance and patients aged 50 to 64 years, suggesting that many providers attending the training were unaware of the need to vaccinate these patients.