USC faculty filed paperwork Tuesday to hold union elections, a move that administrators have warned could lead to increased hostility on campus.
The non-tenure track professors were organized by Service Employees International Union Local 721, which represents bargaining units in Los Angeles and the county.
There are nearly 6,600 full-time faculty at USC and nearly 5,000 are on a non-tenure track, according to the university's website.
Tenured professors enjoy greater job protections and higher pay.
Kate Levin, a part-time lecturer in the writing program, said she makes about $8,000 for each of the four classes she teaches each year.
"Many of us have a...