Born in 1893 in a Baptist parsonage in Greenville, New Hampshire, Sanderson was the daughter of Rev. Elisha Sanderson, a member of the Colby class of 1886. She prepared for Colby at Coburn Classical Institute, a private college-preparatory academy in Waterville long affiliated with the college, and entered in the fall of 1910.
The Y.W.C.A. was the foremost passion of her Colby life, and by her senior year she was its president. As a junior she was a delegate to the Y.W.C.A. conference at Bates and to the national conference at Silver Bay on Lake George, and as a senior she represented the Colby chapter at Gould Academy and at a Y.W.C.A. conference at Simmons College. In December 1913 she spoke at a campus Y.W.C.A. banquet honoring the visiting Northeastern Territorial Secretary, giving remarks titled “The Place of the Association in the Life of the College Girl.” Music and ministry ran together for her at Colby. She joined the Colbiana board and sang in the College Choir her junior year and was a member of the Ladies’ Glee Club in both her junior and senior years, performing at chapel services and campus concerts.
The clearest sign of where her Colby life was heading came on December 12, 1912, when she signed her Student Volunteer pledge. The S.V.M. application she filed showed that she was the only Student Volunteer at Colby, with no S.V.M. band on campus established to support her.