There has long been a tension in higher education between full-time, tenure-track professors who have dedicated their lives to research and teaching, and part-time adjuncts, who typically take up teaching as a secondary career and don’t receive health or retirement benefits.

From 1975 to 2009, the proportion of part-time faculty in U.S. higher education institutions increased from 24 to 41.1 percent, a trend the American Association of University Professors calls “the establishment of a subordinate tier of faculty members.”

The number of adjuncts is high at USC, too — 33 percent of university faculty are part-time and have no tenure or tenure-track designation.

A New York Times book review published in April describes adjunct professors as “holders of advanced degrees who are lured in by the prestige of college teaching, hired on a piecework basis, paid low wages and shut out of academic decision-making.”

But Martin Levine, vice provost for faculty affairs, said that description does not typically apply to adjuncts at USC.

“Many of these people have very active careers of their own,” Levine said. “They usually have marvelous experience and … are delighted to come in and work with students.”

Organizations such as the American Association of University Professors condemn the increase in adjunct hires because they say it means more doctoral graduates are shouldering the burden of teaching without possibility for tenure.

That ranking of positions has traction in English, according to Margaret Russett, a professor and chair of the English department.

“A tenure-track job is the gold standard,” Russett said. “That’s what one would prefer, all things being equal.”

Technically, USC’s English department employs no adjuncts; the division is between tenure-track and non-tenure-track full-time faculty, a practice Russett said the university encourages other departments to adopt.

Many students do not realize that “adjunct” designates just one type of non-tenure-track faculty who do not have a long-term contract with USC. Other titles include lecturer, visiting professor and research professor, all of which the university can confer without offering the salary and benefits typically afforded to tenure-track hires.

The tenure-track job as the “gold standard” is true in English, as well as most social science and humanities disciplines. But Sofus Macskassy, a professor who recently moved into a full-time position at the Viterbi School of Engineering’s Information Sciences Institute, said computer science and technology Ph.D. graduates are often indifferent to the tenure race.

“[Computer scientists who take adjunct professorships] just keep their foot in the door, they get their secondary income, they get to keep [on top of] what’s going on in the research community,” Macskassy said.

For years, Macskassy willingly worked as an assistant adjunct professor in computer science while holding a research position at a startup company. Though he always aimed to become a full-time professor, he also saw the industry-and-academia combination as ideal for recruiting outstanding students into the profession.

In the computer science department, Macskassy said, adjuncts “don’t have any responsibilities. You can teach if you want to and you can do research if you want to, it’s basically an association.”

Ted Ancona, an adjunct instructor of music industry, said the music school hires many instructors from outside to teach just one instrument. Ancona was himself a classical music recording engineer for KUSC when the university asked him to step in and teach a class about his niche specialty.

“If you know everything about history you may focus on that, but in the cinema school or electronics or music industry, there’s a lot of development in the field you’re not caught up with [being in academia],” Ancona said.

Adjuncts have been recipients of the prestigious Teaching and Mentoring Awards granted by the USC Parents Association, Levine said. The shame of not being tenured might change as tenured jobs disappear.

“I don’t think this phenomenon [of tenure decline] is going to go away, and we’re all going to have to adjust to it,” Russett said.