We sought to determine if a simple educational intervention initiated at the first well-child care visit, with reinforcement at subsequent visits, can improve inner-city infant immunization rates. We conducted a controlled trial involving 315 newborn infants and their primary caregivers in 3 inner-city primary care centers. Child health care providers gave caregivers in the intervention group an interactive graphic card with verbal reinforcement. At later visits, stickers were applied to the card when immunizations were given. Routine information was given to controls. After the trial, age-appropriate immunization rates at 7 months were 58% in each group. Intervention infants had 50% fewer missed opportunities to immunize (p=0.01) but cancelled 77% more appointments (p=0.04) than controls. We conclude that a brief educational intervention at the first well-child care visit did not boost 7-month immunization rates, although it was associated with fewer missed opportunities to immunize.