Alan Eisenberg, a lawyer who during his 25 years as the top executive of Actors’ Equity Association helped build its membership and dealt with a controversy involving the racial casting of the hit musical “Miss Saigon,” died on Oct. 7 in Rhinebeck, N.Y. He was 88.

His wife, Claire Copley, said he died in a hospital of lung cancer.

Mr. Eisenberg had worked at law firms for two decades before he was hired in 1981 as the executive secretary (his title was later changed to executive director) of Actors’ Equity, which represents theatrical actors and stage managers.

In the 1980s, the union was confronted with the AIDS crisis, which had a harsh impact on the theatrical community. Mr. Eisenberg was a champion of Equity Fights AIDS, the philanthropic fund formed within Actors’ Equity in 1987 to help members in financial need.

Tom Viola, the executive director of the nonprofit Broadway Cares/Equity Fights AIDS (the two organizations merged in 1992), said in a phone interview that Mr. Eisenberg offered “ballast and direction” to the “emotional understanding of what needed to be done” provided by the actress Colleen Dewhurst, who was president of Equity Fights AIDS from 1985 until her death in 1991.

Mr. Eisenberg was in the news in the summer of 1990, when he led the union’s opposition to the casting of Jonathan Pryce as a parasitic Eurasian pimp in “Miss Saigon,” a musical set largely in American-occupied Saigon in 1975.

The union objected to the casting of Mr. Pryce, who is white and Welsh, as the half-French, half-Vietnamese Engineer, because he was not Asian. Mr. Pryce had worn eye prosthetics and makeup to appear Eurasian in the London production, for which he won an Olivier Award, but he had stopped using this so-called yellowface around the time the controversy erupted in New York.

Mr. Eisenberg called the decision to cast Mr. Pryce in the Broadway production “especially insensitive and an affront to the Asian community.”

When the union refused to permit Mr. Pryce to appear in the show, the producer Cameron Mackintosh countered by canceling the planned $10 million production, which had a huge advance ticket sale.

But after about 150 Actors’ Equity members signed petitions asking the union to reconsider its position, the union relented a week later. Mr. Mackintosh reinstated the production, which opened in April 1991 and ran for 4,092 performances.

Mr. Eisenberg said that the union had received a “good faith commitment” from Mr. Mackintosh to find talented Asian actors to succeed Mr. Pryce when he left the show. All of his replacements were Asian or Asian American.

“Many of us would have been happier had it been an Asian,” Mr. Eisenberg said in a news conference after the union’s council voted to let Mr. Pryce play the Engineer. He added: “We’re very, very unhappy with a lot of things. The lack of opportunity for an ethnic Asian actor to audition for the role and for the mixed signals sent out as to whether the role would be available to an Asian actor.”

Doug Carfrae, the union’s Western regional vice president, said in a phone interview: “We planted our diversity, equity and inclusion flags there. We said, ‘If you need to do this, you have to bring in someone who represents the culture and race being depicted.’”

A similar dispute arose later in 1990 over the union’s rejection of Lea Salonga to recreate her Olivier Award-winning leading role as a Vietnamese bar girl. At the time, Actors’ Equity was restricting the appearances of non-American performers on Broadway if they were not stars, to protect American jobs. (Ms. Salonga was not yet a star at the time.) But an arbitrator ruled that Ms. Salonga could play the role.

Mr. Eisenberg expressed his disappointment with the Salonga ruling. “We certainly believe,” he said, “that there is sufficient and wonderful talent within the Asian American acting community in this country to do this role in extraordinary fashion.”

Mr. Pryce and Ms. Salonga won Tony Awards for best actor and actress in a musical.

Alan David Eisenberg was born on April 15, 1935, in Manhattan and grew up in Brooklyn. His father, Arthur, was a traveling housewares salesman. His mother Malka (Novak) Eisenberg, a Russian immigrant, was a homemaker.

Alan’s interest in the theater was sparked by an elementary-school teacher and by a production of Shakespeare’s “Antony and Cleopatra,” with Laurence Olivier and Vivien Leigh, that he saw as a teenager.

Mr. Eisenberg received a bachelor’s degree in English 1956 from the University of Michigan. He graduated from New York University School of Law three years later.

He worked for two law firms in the early 1960s before taking a job at the National Labor Relations Board, which he held from 1964 to 1968. He then returned to private practice as a management labor lawyer, an experience he found disillusioning.

“I mean, I was a tough-assed, union-busting management lawyer for a really tough law firm,” he recalled in an oral history interview with the American Jewish Committee in 1992. “I did a lot of anti-union campaigns, which in the jargon today is called union avoidance campaigns.” He added: “It didn’t make me feel good to leave work at the end of the day doing that kind of stuff. It was not the way I was brought up.”

He left that firm and formed his own, Eisenberg & Paul, which represented trade unions, including the Newspaper Guild when most of its members at The Washington Post crossed the picket line of pressmen during a 20-week strike in 1975 and 1976.

In 1981, he learned that the executive secretary position at Actors’ Equity was open. He submitted his name to a search committee and was hired.

“And I was very happy to leave the practice of law,” he said in the oral history.

During his time at Actors’ Equity, the union said, membership increased from under 29,000 to 46,000, and earnings for actors and stage managers rose from about $119 million to $250 million. When the union’s health plan was $16 million in debt in 2003, he negotiated higher employer contributions, which steadied the fund.

Mr. Eisenberg was also a visiting professor of theater management at the Yale School of Drama for many years.

In addition to his wife, he is survived by his daughters, Mollie Copley Eisenberg and Emma Copley Eisenberg.

Mr. Eisenberg had been interested in the theater long before he joined Actors’ Equity, but his job there made him a nearly nightly theater habitué.

“It’s exciting, kind of like looking at a menu — what am I going to see tonight?” he told Playbill in 2005. “I’ve been seeing more than 125 productions a year for 24 years. I see everything on Broadway. I see most of the Off Broadway productions. And then I poke around all over the city or out of town, and I see many of the smaller productions, which in a lot of ways are the most interesting. And I usually go backstage.”