"We need to enroll them in the program they're currently eligible for and at the same time we need to do anything possible at the state level to keep eligible kids enrolled," said Sebelius.
The three-day event at the Marriott Hotel kicks off a national effort to boost and retain enrollment in Medicaid and the Children's Health Insurance Program, or CHIP.
Earlier this year, Obama signed legislation enabling about 7 million children to continue coverage through CHIP for the next four years. It also allows millions more to sign up.
Sebelius says it's important to get eligible children covered to boost their chances of staying healthy.
The Associated Press contributed to this report.