Yvonne Emma Theriault, a lifelong Concord resident, died peacefully at CareOne in Concord on Tuesday, September 7, 2021, surrounded by her loving family. She was 90. Born in Concord on July 12, 1931, Yvonne was the daughter of the late Charles and Mary (Comeau) Theriault. She was a member of the Concord High School Class of 1949. Yvonne worked as an operator for New England Telephone Company in Concord from 1950 – 1955. In 1956, she began working for M.I.T. Lincoln Lab as a switchboard operator, retiring in 1996. A devout Catholic, Yvonne was a parishioner at the former Our Lady Help of Christians in Concord. Yvonne is survived by her brother, Charles Theriault of Concord; her nieces, Linda Ballard and her husband John of Maynard, Donna Thompson and her husband Chet of Maynard, Lee-anne Mahoney and her husband Sean of Derry, NH, and nephew Michael Theriault of Littleton. She is also survived by one great-niece and five great-nephews. She was predeceased by her sisters, Mary Theriault and Louise Eddy, brother-in-law Jim Eddy, and sister-in-law Cynthia "Tilly" Theriault. Relatives and friends are invited to gather for a visiting hour on Saturday, September 11th from 10 to 11 am in the Dee Funeral Home, 27 Bedford Street, Concord Center before processing to St. Bernard's Cemetery, Concord where Yvonne's graveside service will be conducted. In lieu of flowers, memorial contributions may be made to a charity of one's choice. Arrangements are under the care of Dee Funeral Home & Cremation Service of Concord.