Mary Margaret Wolfskill, 58, head of the reference and reader service section of the manuscript division of the Library of Congress, died May 23 of ovarian cancer at the Halquist Memorial In-Patient Center, Capital Hospice, in Arlington. She was a longtime Washington resident and had been at the Library of Congress for 36 years.

Miss Wolfskill was the library's specialist on Margaret Mead; she described the famed anthropologist, who died in 1978, as "one of the most documented lives in American history."

The Margaret Mead Collection, one of the largest and most complex collections the library owns, presented a daunting preservation and curatorial challenge when it was acquired in 1982. The collection was a vast assemblage of manuscripts, 30,000 still photographs, 35,000 feet of black-and-white motion picture film, sound recordings, original art, Mead's personal diary and other materials.

Under Miss Wolfskill's direction, archivists were required not only to inventory and process the material but also to conduct research into the field notes and other manuscripts Mead and her husband, Gregory Bateson, had compiled. As archivists seeking to make the collection accessible to the public, they were searching for an appropriate organizing principle. The processing work has taken more than two decades, with work still to be done, as additional materials continue to come in.

"It was a curious process," recalled Catherine Bateson, Mead's daughter and a retired professor at George Mason University. "We started out thinking of Mary as the librarian and archivist, but she increasingly became a member of the family."

Miss Wolfskill often gave talks on the Mead Collection to academic conferences and to her fellow librarians and archivists and led the planning group for the library's Margaret Mead Centennial Exhibit in 2001. "No one is ever going to know the collection as well as Mary did," Bateson said.

Miss Wolfskill was born at Fort Benning, Ga., and graduated from Francis C. Hammond High School in Alexandria. She received a bachelor's degree in history from Radford University in 1968 and a master's degree in management and supervision from Central Michigan University in 1979. She received a master's degree in women's studies from George Washington University in 1980.

She became a manuscript reference librarian in the manuscript division of the Library of Congress in 1968. Two years later, she became an archivist in the division's presidential papers section, where she prepared collections of presidential papers for indexing and microfilming.

From 1971 to 1984, she was an archives specialist. Her duties included writing guides to collections, recommending materials for disposition, conservation or microfilming and training new archivists.

From 1984 to 1988, she was assistant head of the reference and reader service section in the library's manuscript division, where she was responsible for the daily operation of the Manuscript Reading Room. In 1988, she became head of the section, a position that called on her skills as a generalist familiar with the library's vast and varied holdings.

She was the author of "The Papers of Frederick Law Olmstead" (1977), "The Papers of George Kleine" (1979) and "Meeting a New Century: The Papers of Four Twentieth-Century First Ladies" (1989).

Miss Wolfskill was a member of St. Stephen Martyr Catholic Parish in Foggy Bottom. She also was active as a volunteer at National Cathedral, where she was an usher, and at St. Paul's Episcopal Church, where she was a member of the Grate Patrol, a program that prepares and delivers breakfast to the homeless every weekend in downtown Washington. On Saturdays and Sundays for many years, she got up at 4:30 in the morning to get the food delivered.

Survivors include a sister, Ethel W. Hedlin of Arlington.

Mary Wolfskill led the Library of Congress's work on its vast collection of papers and other material from anthropologist Margaret Mead.