Harry S. Wender, 77, a Washington attorney for more than 50 years and who was prominent in civic, volunteer, and professional organizations both locally and nationally, died of cardiorespiratory arrest Dec. 14 at Suburban Hospital. He lived in Rockville.

In a town seemingly filled with lawyers of international renown, Mr. Wender made his quiet mark as a leader of local causes. Admitted to the D.C. Bar in 1932, he never retired. Along the way he received a roomful of awards from his community and profession.

These included the outstanding trial lawyer of the year award from the D.C. Association of Plaintiff's Trial Attorneys and the old D.C. Commissioners Certificate of Merit "for unselfish and devoted service to his community." D.C. Mayor Marion Barry designated Oct. 4, 1983, as Harry S. Wender Day for Mr. Wender's community work.

Mr. Wender was the founding chairman of the old District of Columbia Recreation Board, a job he held from 1942 to 1952. This was an appointed, nonpaying, thankless job. Among Mr. Wender's self-appointed goals was to end segregation in city recreation facilities. He did this by ending segregation where he could, and increasing facilities for blacks at segregated facilities when he could not. This was accomplished without disorder or great fanfare.

He was a past president of the D.C. Federation of Citizens Associations. For a number of years, to highlight outstanding work done by local police, he worked with the organization which named a "policeman of the month." The award gave publicity to heroic officers and carried a cash award of $100. The money came, quietly, from Mr. Wender's pocket.

An authority on traffic law, over the years he served on the D.C. Engineering, Transportation & Parking Commission and the Mayor's Citizens Traffic Board, and had chaired the D.C. Bar Association's committee on motor vehicle law and traffic court. In those posts, he fought for improved highways and more sophisticated car insurance laws. He also successfully called for courts to go into session on nights and weekends to handle cases of defendants unable to attend court during regular hours.

Mr. Wender was a past president of the Association of Plaintiff's Trial Attorneys of Metropolitan Washington and had been an officer of the American Trial Lawyers Association. He had been a committee chairman of the Federal Bar Assocation, a committee vice president of the American Bar Association and an editor of the D.C. Bar Journal.

Long active in B'nai B'rith, Mr. Wender had been president of Argo Lodge and District Grand Lodge No. 5. He was a cofounder of the B'nai B'rith member's insurance program and had served on B'nai B'rith's international board of governors. He was a founder, general counsel and trustee of the B'nai B'rith Foundation of the United States. He was a founder of the Jewish Historical Society of Greater Washington and served as archives committee chairman of the Washington Hebrew Congregation.

Mr. Wender was born in Knoxville, Tenn., and moved to Washington as an infant. He attended George Washington University and earned his law degree at Georgetown University.

His wife, the former Gertrude Schwartz, died in 1983. His survivors include two daughters, Marilyn W. Cohen of Philadelphia and Elaine S. Wender of Maui, Hawaii; a sister, Jennie Diamond Millstein of Silver Spring, and three grandchildren.