We are the stoop laborers of higher education: adjunct professors.

As colleges and universities rev for the fall semester, the stony exploitation of the adjunct faculty continues, providing cheap labor for America's campuses, from small community colleges to knowledge factories with 40,000 students. The median salary for adjuncts, according to the American Association of University Professors, is $2,700 per three-credit course. Some schools raise this slightly to $3,000 to $5,000; a tiny few go higher. Others sink to $1,000. Pay scales vary from school to school, course to course. Adjuncts teaching upper-level biophysics are likely to earn more than those teaching freshman grammar.

There is no uniformity, but similarities abound. Benefits, retirement packages, health insurance? Hardly. Job security? Silly question. An office? Good luck. A mailbox? Maybe. Free parking? Pray. Extra money for mentoring and counseling students? Dream on. Chances for advancement? Get serious. Teaching assistants? Don't ask.

AAUP reports that part-timers now make up 50 percent of total faculty. As adjuncts proliferate, the number of tenured jobs falls. Why pay full salaries when you can get workers on the cheap?

Hordes of adjuncts slog like migrant workers from campus to campus. Teaching four fall and four spring courses at $2,700 each generates an annual salary of $21,600, below the national poverty line for a family of four. In a classroom across the hall, a tenured professor could make $100,000 for teaching half as many courses to half as many students. The tenured commonly speak of their teaching "loads," as if they were hauling burlap sacks of weighty tomes up to the heights of Mount Academia.

In "Equality for Contingent Faculty: Overcoming the Two-tier System," Keith Hoeller, an adjunct at Green River Community College in Auburn, Washington, writes that "throughout the country college administrators, often with the collaboration of academic unions, have gone to great lengths to keep their increasing numbers of adjunct faculty secret from students, parents, legislators, accreditors, foundations and the public."

Schools boast of having, or nearly having, 100 percent Ph.D.s on the full-time faculty but stay mum on their numbers of adjuncts, even though the distinction has little to do with the talents of the professors. Earning a doctorate, too often a form of intellectual hazing, confers ascensive status, not teaching ability.

Generally, schools hire two kinds of adjuncts: the penuriously trapped who rely on their table-crumbs pay and those who have incomes elsewhere. By grace and a tick of luck, I'm in the second group, being an adjunct since the mid-1980s at American University, the University of Maryland and Georgetown University Law Center, as well as two public high schools. This fall and spring I expect to teach 13 peace studies courses. My university pay totals $28,300.

No matter. Besides feeling privileged to be teaching at all, considering my less-than-sparkling grades in high school and college, my lasting compensation comes in a wealth of deep satisfaction in teaching what I care about and savoring the company of my students. Adjuncts like me tend not to be credentialized with graduate degrees but are hired for our experiential knowledge in our professional, not professorial theoretical, lives.

Recent years have seen efforts to deliver economic fairness for single-income adjuncts at the grubby bottom of campus employment. One organizing force is the nonprofit New Faculty Majority, led by Maria Maisto, an adjunct at Cuyahoga Community College in Ohio. On April 16, she said on NPR: "When my husband lost his job, I had to try to support my entire family as an adjunct with no access to health insurance. I have kids. I know many adjuncts who have been on food stamps ... This problem has evolved in such a way that families and our society are subsidizing what colleges and universities won't provide."

For strapped adjuncts with no off-campus income, a solution is to replace a minimum wage with a living wage - say, $15,000 a course plus benefits. Where would the money come from? Start with cuts to presidential salaries, which are at all-time highs. Annual pay packages from $500,000 to more than $1 million are common. Meanwhile, the loan debts of students - the pre-unemployed - soar.

Until salaries at the top are trimmed - including excessive pay to big-time football and basketball coaches - and those at the bottom are raised, the demeaning of adjuncts is little more than structural economic violence. It's to be wondered why the collective conscience of a college or university is rarely stirred by the salary inequality that has persisted, and even grown, for decades, with little relief in sight. Some union organizing is happening. Though promising, to date it is mostly an exercise in tinkering. At graduations, students are grandly implored to go make the world a better place. Every place, dear children, except your alma mater.

Colman McCarthy, a former editorial writer and columnist for The Washington Post, directs the Center for Teaching Peace in Washington.