How Do you know if a social program is a success? Congress and the new administration will have to give some thought to that next year as they weigh the hundreds of existing social programs in the budget balance. Why not start by considering the history and performance of the Job Corps, a mainstay of the 1960s' War on Poverty -- it is instructive.

Like many of the Great Society programs, the Job Corps was launched with much noise and too much expectation. Unlike others, it has survived and matured to the point where it is, in fact, a reasonable taxpayer investment.

The Job Corps takes school dropouts from poor families, moves them away from their familiar surroundings to one of over 100 camps and tries to help them acquire skills you need to have to hold a job. As a recent Post series by Dale Russakoff observed, the progrom's first few enrollees were a disappointment to its sponsors. Many quickly got homesick and went home to the ghetto or the coal field community. Fifteen years later, many of the group think the program was a waste of time. Others feel it made an important change in their lives. But on the basis of this first experience, no one would conclude that the program was a roaring success.

Fortunately, the program's administrators paid attention to their early mistakes and tried to fix them. They recruited counselors wise to the ways of the "street" who knew how to head off racial strife and deal with youths with long histories of failure and few grounds for self-respect. They signed contracts with unions and industry to provide up-to-date training and a better chance of getting a job afterward. And they recognized the need to set and enforce clear standards of success and failure for both the people who run the Job Corps centers and the youths who enroll.

A Job Corps still isn't for everyone -- homesickness, resistance to discipline and weak motivation still produce a high dropout rate in the first few months. And it's far from cheap -- about $10,000 for the average enrollee who completes the course. But for the kids who hang in there, Job Corps does have a solid record of success -- about 70 percent are placed into jobs, at an average wage of $4.65 an hour; another 20 percent enter the military or continue their education. Studies show that compared with a like group of youths not enrolled in the program, Job Corps graduates have significantly higher earnings and subsequent education, and significantly ower chances of being on welfare, having an illegitimate child or being arrested. Not an automatic ticket to the middle class, to be sure, but a long step in a good direction.

For a program of this type, this is surely "success." True, it's not easy to achieve, and it doesn't occur overnight. It requires an unsentimental scrutiny of how a program is going and a willingness to fix things that don't work. Most of all, it requires a realistic assessment of what, in this imperfect world, a social program can hope to achieve.