Seymour P. Lachman, a former New York State senator who was so fed up with the political shenanigans in Albany that he quit the Legislature and wrote two books that helped spur reforms, died on Jan. 2 at his home in Manhattan. He was 91.

His wife, Susan Lachman, confirmed the death.

Mr. Lachman (pronounced LACK-man), a college professor who had also briefly served as president of the New York City Board of Education in the 1970s, was first elected to the State Senate in 1996 to fill a vacancy in a Brooklyn district that originally included the Bensonhurst and Borough Park sections and later also included part of Staten Island.

A Democrat, he often described himself as a traditionalist. But he would have been the first to acknowledge that the tell-some book he wrote about secretive power-brokering in Albany probably had more impact than his party-line votes as a legislator.

The title of the book — written with Robert A. Polner, a Newsday reporter — was a giveaway: “Three Men in a Room: The Inside Story of Power and Betrayal in an American Statehouse” (2006).

Its thrust was that anything of consequence that occurred in the state capital was predetermined by the governor, the Senate majority leader and the Assembly speaker and reflected “a subservience by lawmakers that has no peer in the United States Congress nor in many American statehouses.”

The book told of the corrupting power of money, the outsize influence of lobbyists, and public authorities’ lack of accountability.

“The reward for lawmakers’ compliance includes party assistance and taxpayer-financed pork-barrel morsels for community organizations in election years,” Mr. Lachman and Mr. Polner wrote in an opinion essay in The New York Times in early 2007.

They added: “Those who play by the rules of the leadership also benefit by having their names appended from time to time to bills of importance. They receive committee assignments that can earn them as much as $40,000 on top of their $79,000 yearly salary, and their district lines are rigged in their favor for lifetime job security. Is it any wonder that while Democrats won big across the country this November, in Albany just one Republican seat in the State Senate went Democratic?”

“Three Men in a Room” vividly described Albany’s backstage machinations and argued for change, some of which Gov. Eliot Spitzer and later Gov. Andrew M. Cuomo said they favored.

The two authors also wrote “Failed State: Dysfunction and Corruption in an American Statehouse” (2017), in which they lobbied for revisions in New York’s bloated and anachronistic Constitution.

At his death, Mr. Lachman was director emeritus of the Hugh L. Carey Institute for Government Reform, which he founded in 2008 at Wagner College on Staten Island.

“His books added fuel to the fire,” Blair Horner, legislative director of the New York Public Interest Research Group, said in an interview. “His bird’s-eye insights coupled with the research produced by the Carey Institute bolstered the need for reforms. The work contributed to an atmosphere that resulted in some changes — flawed, but changes — to redistricting, campaign finance and ethics.”

Those changes were nudged along by embarrassing indictments of leaders in the Senate and Assembly, who had largely opposed major reforms.

As a member of the Board of Education from 1969 to 1974 and its president from 1974 to 1975, when he resigned to spend more time teaching, Mr. Lachman proposed the appointment of an educational ombudsman, worked to alleviate religious and racial tensions in the schools, and was the principal architect of a resolution on the rights and responsibilities of senior high school students and on the workings of peer group programs that provided drug education and draft counseling during the Vietnam War.

After leaving the board, he was appointed to a joint professorship in the history and politics of education, teaching at both the City University’s Graduate Center and Bernard M. Baruch College, where he was later named university dean for community development. He also taught at Adelphi University, on Long Island.

Seymour P. Lachman (the middle initial did not stand for a name, his family said) was born on Dec. 12, 1933, in the Bronx to Jewish immigrants from Poland. After losing his candy store during the Depression, his father, Louis, worked as a steam presser in the garment industry and as a ditch digger. His mother, Sarah (Koniarsky) Lachman, looked after the household. The family moved to Brooklyn when Seymour was an infant.

After graduating from Thomas Jefferson High School in Brooklyn, Mr. Lachman earned bachelor’s and master’s degrees in history from Brooklyn College, in 1955 and 1958, and a doctorate in history from New York University in 1963.

He taught in Brooklyn public high schools until 1963, when he was hired as a professor of history at Kingsborough Community College in Brooklyn, part of the City University system. Two years later he was appointed dean of its mid-Brooklyn campus.

Early in his career, Mr. Lachman was director of the foreign affairs department of the American Jewish Committee. From 1980 to 1983, he headed the Greater New York Conference on Soviet Jewry.

His other books include “One Nation Under God: Religion in Contemporary American Society” (1993, with Barry Kosmin), based on the 1989-90 National Survey of Religious Identification conducted by the Graduate Center; “The Man Who Saved New York: Hugh Carey and the Great Fiscal Crisis of 1975” (2010), with Mr. Polner; and “Mr. New York: Lew Rudin and His Love for the City” (2014), about the real estate developer who was a behind-the-scenes force during the city’s fiscal crises in the 1970s and early ’90s.

Mr. Lachman married Susan Altman in 1961. In addition to her, he is survived by their children, Rabbi Eliezer Lachman and Sharon Lachman Chesir; 11 grandchildren; and three great-grandchildren.