Instructors with the English Language Institute at American University voted 29-to-1 yesterday in favor of unionization, bringing them one step closer to becoming the first teacher group in the school's 89-year history to achieve collective bargaining status.

The vote means that the English Language Institute Faculty Association, which was formed last September, will represent the 35 teachers in the Institute providing the election results are certified by the National Labor Relations Board. The NLRB had representatives at yesterday's election, and certification is expected to be a formality, according to an association spokesman.

Association members, who teach English as a second language, filed a petition last February seeking to be represented by their own union. The university administration challenged their request. After a six week hearing, the NLRB approved the association's request late last month, and the representation election was ordered.

A spokesman for the university said yesterday that there would be no comment from the administration on the vote results.

"We hope now to be able to improve the terms and conditions of our employes," Myra Shulman, president of the association, said after the vote was in.

Members of the association, she said, feel they have been treated unfairly in that they are not considered part of the university's faculty. "None of us receive faculty benefits," said Sally de Luca, treasurer of the association. "The part-time members have no job security, no pension, no tenure, no grievance procedure, nothing. Our vote is an effort to get equity among ourselves and with our colleagues." A university spokesman said that there would be no comment on these assertions.

Although the trend toward the unionization of faculty at the university level is a decade old, only 20 to 30 percent of the teachers are represented by unions that may bargain collectively, according to Irving Spitzberg, general secretary of the American Association of University Professors. In the District, only professors at the University of the District of Columbia have such representation, he said. The National Education Association represents them.