William Wilkoff, 79, a Washington industrial and commercial designer with a passion for making sure that buildings and public places were accessible to the disabled, died June 24 at Georgetown University Hospital. He had cancer.

Mr. Wilkoff began his career as a designer in 1951. He got involved with barrier-free issues in 1972, when he became the liaison between the American Society of Interior Designers and the President's Commission on Employment of the Handicapped.

In that role, he came to know and admire the late Harold Russell, a disabled World War II veteran who received two Academy Awards for his portrayal of a double amputee in the 1946 film, "The Best Years of Our Lives." Mr. Russell, who lost his hands in an Army demolition accident, was the unpaid chairman of the President's Commission on Employment of the Handicapped from the early 1960s to the late 1980s.

For Mr. Wilkoff, the culmination of his interest and involvement in barrier-free design was the landmark Americans With Disabilities Act, signed into law by President George H.W. Bush in 1990.

Mr. Wilkoff served on the National Codes Commission for the ADA and worked with designers and architects, landscape architects and architectural students across the country on ways of designing for the disabled. Invariably, he encouraged his fellow designers to learn the law.

He also served on the D.C. Building Code Advisory Board, where he was chairman of the barrier-free subcommittee and was a member of the President's Committee on Employment of People with Disabilities.

William Louis Wilkoff was born in Youngstown, Ohio. He attended Ohio State University and Pratt Institute, where he received a bachelor's degree in industrial design. During World War II, he served in the Army in Europe.

Mr. Wilkoff's wife, Paula, an interior designer, was a longtime professional partner in Mr. Wilkoff's business, District Design. After Mr. Wilkoff's retirement in 1991, the couple worked together on accessibility surveys of malls, hospitals and other public buildings.

Mr. Wilkoff was the author of the book "Practicing Universal Design: An Interpretation of the ADA" (1994), with a foreword by James Brady, the presidential press secretary who was seriously wounded in the attempted assassination of President Ronald Reagan.

Mr. Wilkoff's interest in removing architectural barriers never waned. "He felt it was irresponsible to assume that every user of a space was able-bodied," his daughter Laura Abed said.

His wife recalled an evening at the Avalon Theatre (before the venerable movie house was shut down and then restored and reopened in 2003) when Mr. Wilkoff witnessed a man using a wheelchair get stuck in the door of the men's room. He helped the man get through the door and then protested to the management about the building's inaccessibility. Since the city's oldest movie house was about to be shuttered, he got no response.

Recently, the Wilkoffs visited the theater again, despite Mr. Wilkoff's illness. He happily reported to his wife that the unisex restroom was indeed accessible.

Survivors include his wife of 54 years; four children, Robert C. Wilkoff of Cabin John, Leslie Wilkoff of North Bethesda, Susan Wilkoff of Bethesda and Laura Abed of Hartford, Conn.; and four grandchildren.