Linda Harris is black, poor and out of a job.

The 30-year-old Durham, N.C., dropout has worked on and off for most of her adult life-as a piece worker in a local poultry-processing factory. When she gets work, it's bound to be dirty and low-paying. But the worst thing is, the job usually is temporary, only for a few months.

Harris is one of a growing number of Americans whom economists have branded the "structurally unemployed."

What that high-sounding label means, in essence, is that Linda Harris-and all her counterparts, white, black, male, female, young, old or middle-aged-doesn't have the skills to get and hold a productive, long-term job.

Labor Department studies show that about two out of every five of these workers are young, aged 16 to 24. A third are women. Another third are prime-aged men. Only one in eight is black, but that figure accounts for a high proportion of the nation's blacks.

Numerically, most of the structurally unemployed live outside the nation's big cities. But low-income, poorly education persons in urban ghettos-particularly those in decaying cities, where job opportunities have moved to the suburbs-are hard-hit, too.

To be counted as structurally unemployed under the Labor Department's definition, a person must have been out of work 15 weeks or more-though not necessarily all at once-and have an income below the poverty level. Many, like Linda Harris in Durham, work for a few weeks at a time, changing jobs often.

Manpower experts agree the best way to help Linda Harris-and others like her-out of this dilemma is to help them acquire a marketable skill, through some sort of formal training. In Harris' case, at least, that's just what happened-under Durham's federally financed manpower program.

The Durham program, run by the city government, snatched Harris from the local unemployment line, provided her with counseling and classroom instruction for her high school equivalency certificate, and sent her to Durham Technical Institute to learn hospital recordkeeping practices.

Now she expects to be taking a job soon as a "central service technician" at the sprawling Duke University medical center-thanks in large part to the manpower program. Her wages will amount to $4 an hour or more-about 25 percent above what she earned at the poultry plant. But the work will be year-round.

Nationally, the government's spate of programs aimed at dealing with the structural unemployment problem ranges across classroom training, temporary public jobs designed to give workers "job experience," on-the-job training grants, wage-subsidies for private employers and summer programs for youth.

Taking them as a whole, Michael Borus, a manpower specialist at Ohio State University who has kept tabs on such efforts, damns the programs with faint praise. The manpower programs have "a marginal impact on these peoples' lives-in terms of hundreds of dollars, not thousands," Borus says.

A good many, such as the program run by San Francisco, Calif., are regarded by manpower experts as models-laden with fresh new ideas and talented administrators to help carry them out. Others, such as that in Miami, Fla., have been wracked by reports of fraud and waste.

Durham's program falls somewhere in between. A modest, no frills effort that costs $3 million a year, it's been free of scandal and political abuse, and "reasonably" run by most standards.At the same time, it's decidedly unspectacular. Experts say it may be typical of what goes on nationally.

Part of Durham's emphasis is on classroom training. The city offers classes to prep one-time dropouts for the North Carolina high school equivalency examination, often taking functional illiterates and training them-sometimes for as long as 33 weeks-to pass the test.

Those who pass the exam either are placed in basic-skills jobs (such as a receptionist) or are sent at city expense to the well-run Durham Technical Institute, which offers courses in a variety of skills and occupations-from dental technician to machinst-all keyed to local job-market needs.

The effort also includes other components-an on-the-job training program that contracts with local businesses to hire and train low-income workers, a counseling division designed to help applicants decide where they'd be best suited, and a handful of youth programs.

L. G. Holleman, the former tobacco workers' union official who heads the local manpower operation, says the most valuable service his agency offers is counseling and "credentialization"-providing workers with certificates they can show prospective employers.

The results have been moderately successful. A follow-up study supervised by Holleman's chief deputy, Jack Stone, shows that of some 190 program graduates whom surveyers were able to find, 133 were working, 49 were still unemployed and 7 had dropped out of the labor force-an unusually good record for any program.

But the Durham program has some problems as well:

Despite the rosy figures the city has compiled, many of the program's participants simply drop out before completing the course. Says Jim Leutze, a member of the state's overall manpower board: "You're dealing with the most difficult segment of the population, so the success ratio won't be high."

And partly because of recalcitrance by private industry, Durham's on-the-job training program has been only marginally successful, compared to, say, the classroom instruction portion of the program. Its summer youth programs for teenagers have been little more than "riot insurance" to prevent unrest.

Perhaps the biggest reason so many manpower programs have failed is that the applicants so often start out from such a low base. Many effectively are illiterate. Most lack a diploma or other job certification. Many haven't held regular jobs before, and don't know what's required of them.

If Linda Harris in Durham is a manpower success, then Don Richardson, 33, a black in San Francisco, isn't-at least so far. Richardson was living on welfare when he finally got into a training program for machinists in November 1977. He completed the course last August-without any fond memories.

"The instructor was trying to change you all around, get you to think on a level where you were just going along with him," Richardson complains. There was little help available in finding a job. "They don't go out and help the students after they've completed the course," he says.

"I got knowledge out of the CETA course, but as far as a job, I haven't gotten one yet," Richardson says. "There were people coming down from the companies and telling us in class, 'When you get out, look us up.' But when you get out, the say they don't remember you and there's nothing open."

The absence of a waiting job is a problem that often faces graduates of federal manpower training programs. But experts say the dearth of jobs isn't all industry's lack of interest. Often, it's a commentary on the quality of the local program's training.

Take Nik Smith's experience in Chicago's manpower program. At 34, Smith had been the manager of the mail-order department of a small business that shut down. When he could not find a job in his field, he tried to retrain for a new occupation or trade. After looking at wage levels, he decided on weliding.

After a good deal of wrangling with a CETA counselor, Smith finally was admitted to a welding course at a local vocational school operating on government contract. But he found the curriculum inadequate and the equipment obsolescent and badly maintained.

After graduation, Smith eventually landed a job at an industrial furnace plant-but only because he could add fractions and read blueprints-none of which was taught in the course. "The school's brochure promises to teach a lot of stuff," Smith says, but little of what was promised actually came through.

Victor Murauskas, director of the school, retorts that employers "are not realizing that our schools are producing entry-level people. The personnel who interview our graduates seem to expect people with five years of experience. Our graduates can do basic work with supervision."

The problem of teaching basic skills runs through comment after comment from managers of local manpower programs. Mike Van Leesten, director of the Providence, R.I., branch of Opportunities. Industralization Center, is another who is unhappy about much of CETA's focus.

"If federal officials really wanted to help," Van Leesten declares, "CETA would give us latitude to provide remediation. We need each man to read and write and to do simple mathematics, as well as to give them hands-on training."

"Instead," Van Leesten continues, "job-training programs are geared to very short-term stuff-get them into training for 15 weeks and out into the world of work. That migh be okay for a certain percent of people who need training, but who'll hire you if you can't read or write?"

What training is needed-specific job skills or basic literacy? Who can best provide it-government, or private schools like Durham Technical Institute? Who should get it-minority groups, which may be the most needy, or the Nik Smiths who already have some skills but need more?

Those are the kinds of questions government policymakers keep asking themselves. At the moment, they don't have any good answers-in part because they don't know what works best or, in some cases, even what really works at all.

Also contributing to this article were Bruce DeSilva, Ron Dusek, Paul Grabowicz, Ann Inspee, Flora Johnson, Jill Kearney, and Austin Wehrwein . CAPTION: Illustration, no caption