This quasi-experimental study examines the impact of Idaho's wellness incentive program, which rewards children with CHIP (Children's Health Insurance Programs) who are up-to-date with well-child visits with $30 in credits per quarter for use toward their CHIP premiums. Between baseline and the second year of implementation, the percentage of CHIP children who were up-to-date with well-child visits increased by 116% (from 23% to 49%), compared with a 13% increase (from 29% to 32%) among children with Medicaid, who were not eligible for the incentive. The incentive program had a greater impact on children who were recommended to have one annual well-child visit compared with those recommended to have two to four annual visits. The program was not, however, more effective for those whose premiums were fully covered by the reward compared with those whose premiums were partially covered. This study provides encouraging evidence to states about using consumer financial incentives for increasing preventive care use.