Whether or not a child with developmental delays qualifies for early intervention varies dramatically from one state to the next, but often researchers say far more kids are eligible than can be served.

The finding comes from a new study analyzing early intervention services across the nation. Researchers from the University of Colorado School of Medicine examined each state’s eligibility requirements for the Individuals with Disabilities Education Act, or IDEA, Part C program, which serves infants and toddlers with disabilities. Then they used data from a long-term government study tracking nearly 11,000 children to identify how many kids were likely to qualify or receive services in each state.

Across the country, anywhere from 2 percent to as many as 78 percent of children per state qualified for Part C services, according to the study published this month in the journal Pediatrics. But most of those children are not taking advantage of the early intervention offerings, however, with no state providing Part C services like speech and occupational therapy to more than 7 percent of its kids.

What’s more, even in cases where eligibility was more restricted, researchers found that far more children qualified for services than were receiving them suggesting that at least some kids in need are being overlooked, the study said.

Nationally, about 2.8 percent of young children are served by Part C.

“States need to look at the criteria they use to determine which infants and toddlers are eligible for early intervention. They need to ask themselves why they have such broad criteria when they can’t serve all children under 3 years who have severe developmental delays,” said Steven Rosenberg of the University of Colorado who led the study. “It may help for states to adopt more uniform eligibility criteria.”