PRESIDENT REAGAN once issued a lofty challenge to the nation's school systems to achieve a high school graduation rate of 90 percent by 1990. That required a drastic reduction in the number of students who drop out of school. With a little more than two years left to go, we aren't even close. Nationally, the graduation rate has hovered around 70 percent, and there has been no substantial rise in the past several years. Urban school districts are even further behind. As many as 50 percent of the students enrolled in large-city school systems drop out before earning a diploma.

If current dropout and graduation rates are maintained, will that at least mean that our schools are maintaining ground in producing an effective and competitive labor force? Several prominent educators say that the answer is no. A recent report produced by federal education officials and 32 school system superintendents said that "more sophisticated skills are needed in our increasingly complex technological age, consigning more dropouts to the low end of the economic ladder" and to an increasingly costly dependence on social service programs. Some 37 college and university presidents and chancellors went further, saying that "we perceive a national emergency . . . to maintain and enhance our quality of life, we must develop a leading edge economy based on workers who can think for a living."

We now know that added attention and educational help -- for youths who are failing and becoming chronic truants in elementary schools -- work best. We also know that parental involvement is essential, even if the parents were dropouts. A study in Chicago noted increased student achievement when parents took high school equivalency classes and helped teach their children how to read. Collaborative efforts that match students with mentors from communities, businesses, churches, government agencies, colleges and universities are also important.

There will be no immediate success, but few undertakings demand as much attention as the effort to keep more children in school. Now that so much more is known, it's time to revive that effor