In the past three or four years, the Prince George's County school system has had to hire 150 new special education teachers and therapists for handicapped children.

In Pennsylvania last year, a federal judge told state education officials they could no longer limit their school year to 180 days because that time was insufficient to accommodate handicapped children who needed year-round training.

In New York, a local board of education was required to pay the tuition at an out-of-state private school for a child with severe emotional disturbances.

Such actions, and thousands more like them around the country, were the result of the Education for All Handicapped Children Act of 1975 and the rules and regulations drawn up by the federal government to implement it.

These regulations are now under review by the Reagan administration as part of its overall study of federal regulation and its costs. In this instance, administration officials are concerned about the "flexibility" of the rules, requiring, among other things, the hiring of certain people with certain kinds of degrees as well as individual plans of learning for each handicapped student. The inflexibility, officials believe, may be contributing to the costs.

The act, like so many others, was a kind of contract. The states would deliver on their obligation to educate handicapped children, whether retarded, crippled, deaf or blind, and to the extent possible make sure that these children received the same opportunity as the non-handicapped.

The federal government, for its part, would put up the money.

The handicapped and advocates for the handicapped are still debating whether the states have even come close to keeping their part of the bargain. But there is virtually no debate that the feds did not keep theirs.

When the law was passed, it was said that by 1981 the federal government would provide more than $3 billion so the school systems could pay for all the special education teachers and sign-language experts. The last appropriation request during the Carter administration was for less than a quarter of that amount.

No one rides herd on the federal government to make it live up to its part of the bargain. But the federal government, by threatening to cut off federal money, and the handicapped, through hundreds of lawsuits, have sought to enforce the rules on the school systems.

Like all regulations, the ones governing this law have been lengthy and complicated, with more than 50 pages of definitions, dos and don'ts. But these regulations cut deeper than most, for they enter a turf that traditionally has been jealously guarded: local education policy. The school systems have protested.

Often the protests sound petty. A school official in Illinois recently complained because, under the act, the state was required to purchase birthday cakes for handicapped students attending a private school at government expense.

Many of the complaints are more substantive. The act and the regulations require special conferences with parents of handicapped children to work out a plan to "mainstream" a child into the regular school environment. If a child's handicap is so severe or the facilities of a system so limited that "mainstreaming" is not possible, private education must be financed.

The regulations and the law, many school officials say, are too precise in some places and too vague in others.

A child's learning environment is supposed to be "the least restrictive," for example, and for another guideline the regulations use only the word "appropriate." But at the same time, says Jane Riggin, a Prince Georges County special education official, the regulations "tell you when to have admission review and dismissal meetings, how many times and when, what components must be in that program, who must put it together, who writes it, who reviews it, and there's an entire section on exactly what parents have a right to."

Advocates for the handicapped say they understand all this and they agree that the federal funding has been woefully inadequate. "The other problem," said Reese Robrahn, executive director of the American Coalition of Citizens with Disabilities, is that the states have been "so regressive" before the act that it costs them dearly to catch up.

"It has worked where a school district has really wanted it to work," Robrahn said.