This interim report, the first of two reports to Congress, uses qualitative and quantitative data to document the development of the Children's Health Insurance Program (CHIP), particularly focusing on changes states have made since Congress reauthorized CHIP in 2009. The report found that CHIP and Medicaid have contributed to reducing the number and percentage of children without insurance. States have also made great progress in enrolling and retaining eligible children, but there is still room for improvement in program retention.