Parents are taking action against the city education department over failed promises to reduce class sizes in the public schools. NY1 Education Reporter Lindsey Christ filed the following report.

Rubnelia Agostini's ten-year-old son has been held back in school so often, he's in the second grade.

This week, he was diagnosed with autism, something his mother thought should have been identified years ago.

"Right now, my son would have been on track if they would have been able to provide my son with all the services that he needed," Agostini said. "And they would have be able to do that if they didn't have so many kids in one class."

Agostini is among a group of parents who filed a complaint with the state education department this month, charging that the city isn't meeting its legal obligation to reduce class sizes in public schools.

"Large classrooms contributed to denial of their sound basic education rights, and that, in fact, if they were in smaller classrooms, it was proven that they would do better," said Wendy Lecker of the Education Law Center.

After a legal challenge, a judge ten years ago ordered the city to submit a plan for smaller classes.

The city promised that by 2012, classes in kindergarten through third grade would be capped at 20 children. The limit was to be 23 students in middle school, and 25 in high school.

"Instead, class sizes have gone up substantially since then," said Leonie Haimson of Class Size Matters.

For example, in 2007, one thousand kids in first through third grades were in classes of 30 students or more.

This past school year, more than 43,000 students in the early grades were in classes that large.

"Sometimes you have kids who are grading each other's homework or my daughter said that sometimes she didn't know she was weak in an area until she got the test back, whereas in a smaller classroom kids get the opportunity to know where they are struggling before they get the test back," parent Joanna Garcia said.

Running for mayor four years ago, Bill de Blasio pledged to reduce class size.

But smaller classes have not part of his education reform agenda.

"It's not just a political promise that the mayor made," Haimson said. "I believe it's really his ethical obligation as well."

The city says it's investing $4.5 billion in building more schools in overcrowded districts.

Aides to the state education commissioner said she is reviewing the complaint.

Parents say if there is no relief, they may go to court.