One of two major academic labor strikes planned for New York City this week was averted as the United Automobile Workers, which represents both graduate students at Columbia University and part-time professors at New York University, came to a tentative agreement with NYU on Wednesday. A strike went ahead as planned, however, at Columbia.

Part-time professors at NYU won the right to bargain collectively in 2002, becoming the nation's largest such adjunct union at a private institution. After more than 30 bargaining sessions over 18 months, the two sides finally agreed on a first contract, which is expected to be formally ratified by members of UAW Local 7902 in the next few days.

Both the union and NYU said they were pleased with the multiyear agreement, which would provide a package of wage increases and benefits. Both sides declined to give details until after union members have had a chance to ratify the contract.

Bargaining sessions continued until early Wednesday morning, the day on which the strike had been scheduled to begin. An agreement was reached at 6:40 a.m., when protest signs had already been written and leaflets printed out.

"In the end," said John Beckman, the university's spokesman, "the hard work paid off."

"The adjuncts did an incredible job of standing together," said Scott Sommer, a union spokesman. "They should be really proud of what they've done."

At Columbia, graduate students walked away from their teaching- and research-assistant duties on Monday.

Union organizers said hundreds were participating in the walkout, but Susan Brown, a spokeswoman for Columbia, played down its impact on the campus.

Ms. Brown said the university had made contingency plans to deal with the strike. The primary concern, she said, is making sure that undergraduates are kept informed and that their classes are not disrupted.

Neither side could say how many classes had been canceled or affected by the walkout.