Yale graduate students are calling for a vote that would allow those who serve as teaching assistants to form a union.

To express support for a vote, more than 500 graduate students staged a protest in front of Yale's health center and law school yesterday. The move to unionize has been largely prompted by what grad students are calling university "inaction" on health insurance issues.

Michelle Stephens, chair of the Graduate Employees and Students Association (GESO), said in an interview yesterday that Yale administrators are stonewalling the students.

"We have spent the past year organizing this rally to protest the inaction of the administration on graduate student concerns." Stephens said.

The graduate students are demanding a better health package with fewer restrictions. Under the current plan, same-sex couples are not covered, and graduate students who stay past six years or have families incur higher charges, according to a GESO statement.

Two years ago, Yale grad students won a pay increase after launching massive protests against the school. At the time, the university administration also promised to improve students' health care package, but never followed through, according to the statement.

Stephens said the administration's inaction has made it necessary to form a union.

"They see that the pressure is off," she said of the administration, "so they've become complacent."

Yale officials could not be reached for comment.

Harvard's graduate students do not have a union, according to Thomas Neel, associate dean of administration and finance for Harvard's Graduate School of Arts and Sciences. And Neel said yesterday that he was unaware of any attempts by graduate students to unionize.