SHREWSBURY - Mary R. (Reed) Lambert, 100, died Monday, April 16, at home.

She was born in South Weymouth, daughter of Theodore W. and Katrina (Rodenbach) Reed. Mary was a graduate of Rogers Hall, and received a B.A. from Smith College, cum laude, in 1934, and a B.S. from the Simmons School of Social Work in 1935. She married Benjamin deForest Lambert M.D. in 1935, and they lived together in Boston, Lowell and Chelmsford before settling in Westford in 1947. She moved to Shrewsbury in 2006.

Mary worked for the social services department of Mass General Hospital, the Peter Bent Brigham Hospital and the Lowell Cancer Clinic before starting her family. Both professionally and while raising her children, Mary remained active and committed to many service organizations devoted to the development and education of children and youth. Mary was a board member of the Massachusetts Society for Prevention of Cruelty to Children, a troop leader, neighborhood chairman, and board member of the Greater Lowell Girl Scout Council, a den mother for the Cub Scouts, a member of and secretary for the Westford PTA and a Westford School Committee member for nearly a decade. She was also the first president of the Westford American Field Service organization and her household was the first in the area to host a foreign exchange student in 1960.

Mary and her husband Ben were married for 56 years and, while in Westford, they renovated and restored an 18th century house, which became a welcoming homestead for four generations of family and many close friends. From that home, Mary was proud to offer creative work-share living arrangements that helped many young couples have a way to save financially so they could purchase their own houses. Mary was a connoisseur of words and their meanings, delighting in winning many dinner table bets on definitions, and solving word games and crossword puzzles. Mary was forever a student of the natural world, researching and enjoying flora and fauna discovered on hikes and walks in Westford and in the Squam Lakes region of New Hampshire. Mary was a conservationist and environmentalist, and with her husband was one of the founding members of the Little Squam South Shore Association in New Hampshire. She enjoyed many summers on the lake with family and friends, who affectionately called her “Mimi”.

In October 2011, Mary celebrated her 100th birthday with a party with her extended family.

Mary is survived by her children, Benjamin deF. Lambert Jr., and his wife Linda, Charles H. Lambert, D.M.D., and his wife Diana, all of Amherst, NH, and Deborah A. (Lambert) Sharpe Callahan, of Shrewsbury. She is also survived by eight grandchildren and 14 great-grandchildren. She was predeceased by her husband, Benjamin deF. Lambert, M.D., her brothers Theodore W. Reed Jr. and Philip M. Reed, and her grandson, Bradford C. Lambert.

The family is most grateful to Mary’s care assistants, Caroline, Wanda, Josephine and Evelyn.

A memorial service will be held at 11 a.m., Thursday, April 19, 2012, at Callahan and Fay Brothers Funeral Home, 61 Myrtle St., Worcester, MA 01608. Burial will be private.

In lieu of flowers, donations may be made to the Arthritis Foundation, P.O. Box 96280, Washington, DC, 20077-7491, or to the Squam Lakes Conservation Society, P.O. Box 696, Holderness, NH, 03245.