(AP) Time off? What's that? Melinda Marie Jette, an adjunct professor at Western Oregon University, is teaching four courses this semester, and on the three days a week she has no classes, she grades papers, works on her own research and applies for tenure-track jobs.

Jette, who teaches early American history, is a member of a growing army of part-time professors at the nation's universities. Like her counterparts across the nation, she makes far less than her tenured colleagues and is kept guessing as to whether she will still be employed a few months down the line.

"All I do is work. That's all I do. It's not stable, professionally, or financially," said Jette, who got her Ph.D. from the University of British Columbia in Vancouver in 2004.

The number of adjuncts is on the rise nearly everywhere, as state universities search for ways to keep tuition and costs down and deal with falling state support. Lower-paid adjuncts like Jette free up their tenured colleagues for upper-level courses and research.

The American Federation of Teachers, which represents more than 50,000 adjuncts around the country, says that 43 percent of college faculty members around the country are part-time, non-tenure-track professors, up from 33 percent a decade ago.

And a 2004 report for the Cornell Higher Education Research Institute found that adjunct faculty members were paid about 64 percent less per hour than full-time assistant professors on a tenure track.

Faculty retirements and state budget woes have left campuses relying more and more on adjuncts, said Susan Weeks, a vice chancellor for the Oregon University System. "We have been able to sustain the enrollment we've had, largely with that shift from the full-time ranks to increasing numbers of part-time adjuncts," she said.

Such part-time teachers have always been a staple of community colleges. But adjuncts' numbers are now increasing at the research universities that are the cornerstones of state higher education systems.

In Massachusetts, for example, the flagship University of Massachusetts at Amherst has reported replacing more than 200 full-time faculty members with temporary part-timers in the past decade.

And the University of Kentucky in Lexington now has about 500 part-timers, many in disciplines such as English, math and foreign languages, where there are large numbers of big, introductory-level courses for freshmen.

A very few states have tried to buck the trend, like Oklahoma, where legislators recently released $13.2 million, enough to hire 160 new professors and decrease reduce the adjunct rolls by about 100.

Adjunct professors include novelists, architects, former politicians and other midcareer professionals. Universities say they can bring up-to-date real-world experience to the classroom.

The American Association of University Professors has charted the rising number of adjuncts with alarm, questioning whether the trend harms the quality of instruction.

"We have a lot of reports from part-time faculty who tell us that they are very concerned that if they say something controversial, or if they are too hard on the students, they won't be rehired," said John Curtis, director of research.

But students at Western Oregon said the quality of the instruction depends on the teacher.

Laura Oeffner, 20, said Jette "knows how to handle a class, keep our attention, make a discussion section work."

"But we're in this other class where the teacher is part-time, and it always seems like the lecture is just thrown together, or scrambled," said Michaela Egan, 22.

At Oregon's seven public universities, the number of adjuncts rose from 25 percent of the faculty in 1999 to 33 percent in 2004. Western Oregon has the highest percentage, at 53 percent.

Some of the adjuncts are working or retired professionals who teach a course or two; others, like Jette, are hoping to land a tenured post. Many hold down at least one other job, teaching or otherwise, to make ends meet.

Charles Varani, who has been an adjunct in Western's English department for 14 years, said he likes teaching students how to write a basic essay and is looking forward to conducting a class next semester on the writings of Ken Kesey, whom he studied under at the University of Oregon in Eugene.

But the low pay and job insecurity are troubling, Varani said.

"If they believe you're qualified to teach the material, they could pay you commensurately," he said. "And when we get our evaluations, if we get good ones, they go in some drawer someplace and it doesn't mean anything."