Mary Ann Cook Baker (1830-1902) was born in Boston, Massachusetts, and died in Dorchester, Massachusetts. She was the second wife of Samuel D. Baker, Mary Baker Eddy's eldest brother. When Mary A. Baker was a young child, her parents, Joseph and Mary Cook, were lost in a shipwreck, which Baker survived. She was adopted by Dr. Abner Root and his wife, Christian, and she spent her childhood in Conway, Massachusetts. As a young woman, she served at the Chuahla Female Seminary at Pine Ridge, a Presbyterian mission in the Choctaw Nation, Indian Territory (close to modern day Doaksville, Oklahoma). In 1855, she united with the Park Street Church in Boston, Massachusetts. There she met Samuel D. Baker, whom she married in 1858. In October 1862, she and Samuel accompanied Mary Baker Eddy (then Patterson) on Eddy's first visit to see Phineas Parkhurst Quimby at his office in the International Hotel, Portland, Maine. After the death of Samuel in 1868, Eddy remained close to her sister-in-law, corresponding regularly with her until Baker's passing.

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