A growing number of states are meeting their responsibilities to provide special education services, federal officials say.

In letters sent to each state this month, the U.S. Department of Education indicated that 38 states met their obligations to serve students with disabilities for the 2011-2012 school year. That’s up from 29 the year prior.

Each year, the Education Department assesses how well states fulfill their plans under the Individuals with Disabilities Education Act and assigns one of four ratings: “meets requirements,” “needs assistance,” “needs intervention” or “needs substantial intervention.”

States are graded based on a number of factors including whether or not special education evaluations are conducted in a timely manner as well as dropout and graduation rates and performance on assessments.

For the seventh year in a row, the Education Department said that the District of Columbia “needs intervention.”

The remaining states — Colorado, Delaware, Maine, Massachusetts, Oklahoma, Texas, West Virginia, Illinois, Indiana, Iowa, Louisiana and New York — were deemed to need assistance in implementing the IDEA.

If a state fails to meet requirements for two or more consecutive years, federal law requires that the Department of Education take enforcement action which can include requiring a corrective action plan or withholding funds, among other steps.