This study was conducted to determine whether implementing a program aimed at providing a variety of incentives to physicians who provide immunizations to preschool-aged children would help to improve immunization rates and reduce fragmented care for patients. Twenty physicians from 14 private practices that provide care to preschool-aged children from low income families in suburban Cook County, Illinois participated in the project. A randomly selected subset of patient case records from the physicians' offices were audited after the implementation of the project to determine the immunization status of children in the practices and the nature of services provided. These 310 records of children under three years of age who were treated between 1991-1994 (the intervention sample) were compared to 310 charts from a 1988-1990 cohort of records (baseline sample). The groups did not differ on race or gender; however, significantly more families in the 1988 through 1990 cohort of children under 3 years of age were insured privately when compared to the 1991 through 1994 cohort. Seventy percent (218) of the records in the intervention sample were up to date for age on immunizations compared to 45% (141) of the baseline records, reflecting a statistically significant difference (p < .00001). The intervention sample showed significantly more well child visits where immunizations were given and follow up visits where immunizations were given when compared to the baseline sample. Physicians completed surveys before and after implementation of the project. They were questioned about their knowledge and practices regarding immunizations as well as their opinion of specific project components. All of the physicians viewed the project as an effective means to improve immunization services to low income children. The project demonstrates a potential means of enhancing immunization levels and continuity of care among preschool-aged children. It also highlights the workable nature of the partnership between public and private sectors.