Harry L. Kingman, 90, a former New York Yankee baseball player, a YMCA official and a Washington lobbyist who used a notable combination of friendly persuasion and information in behalf of civil rights and similar causes, died Dec. 27 at the Piedmont Gardens Retirement Center in Oakland, Calif. He had a heart ailment.

Mr. Kingman and his wife, Ruth, moved to Washington in 1957 and founded the Citizens Lobby for Freedom and Fair Play. They funded it with their retirement and Social Security monies and with contributions that never totaled more than a few thousand dollars a year. Their purpose was to represent the public in such matters as civil rights, the use of natural resources, the preservation of the U.S. Supreme Court and other momentarily controversial institutions, and bipartisan matters.

"Participation in government by ordinary Americans is not only possible but essential," Mr. Kingman used to explain. "Our project operates on a financial shoestring and I hope that it always will."

And so the Kingmans set out from the modest apartment where they lived and worked in Southwest Washington to make their views known in the halls of Congress. Over the next several years, they were credited with playing an important role in developing support for the 1957 Civil Rights Act, the first of its kind in 82 years. They continued their work until all of the civil rights laws of the 1950s and 1960s were on the books.

So jealous was Mr. Kingman of his independence--and the importance of this independence on his credibility--that he declined a $500 contribution from the NAACP, whose aims were so close to his own.

"We are convinced," he wrote to the late Roy Wilkins, then the executive secretary of the NAACP, "we would lose some of our influence, based on our somewhat unique independence of action, were we to accept gifts from any legislatively active organization."

"The People's Lobby--it really was that," said former Rep. John E. Moss (D-Calif.), who knew the Kingman's well. "It tried to take a strong consensus viewpoint of what would constitute a public position on these questions. Harry Kingman was probably one of the most informed, and most patient, persons in approaching solutions to government problems that I had the privilege of associating with."

Mr. Kingman was born in Tientsin, China, where his parents were missionaries. He was educated at Pomona College and then joined the New York Yankees for the 1914-1915 seasons. In 1916, he began a long career with the International Committee of the YMCA, Student Division, at Stiles Hall, the YMCA facility at the University of California at Berkeley. He served in the Army in World War I and from 1921 to 1927 was a YMCA representative in China. In 1922, he married his wife in Shanghai.

He returned to Stiles Hall after China and took a master's degree in political science at Berkeley, concentrating on economic and social problems in China. For 20 years he coached the freshman baseball team at UC. During World War II, he spoke out against the internment of Japanese-Americans and then spent two years as the West Coast regional director of the Federal Fair Employment Practices Commission.

In 1957, he retired from Stiles and began his career in Washington. About 1970, he returned to Berkeley and for the past four years had lived in Oakland.

In addition to his wife, of Oakland, survivors include three grandchildren and one great-grandson. A daughter, Beverly Kingman Thiermann, died in 1978.