A study in Health Affairs examined the rates at which children in each state participated in Medicaid and the Children’s Health Insurance Program (CHIP), and how many children were eligible for the programs but did not enroll.  The study found that in 2008, there was an average  of 7.3 million uninsured children, 4.7 million, or 65 percent, of whom, were eligible for but not enrolled in Medicaid or CHIP. 

Kenney, G., et. al. (2010). Who and where are the children yet to enroll in Medicaid and the Children's Health Insurance Program?. Health Affairs. doi: 10.1377/hlthaff.2010.0747 http://content.healthaffairs.org/content/early/2010/09/03/hlthaff.2010.0747.abstract

Authors: Genevieve M. Kenney, Victoria Lynch, Allison Cook, and Samantha Phong