She held a Lick Observatory fellowship,[2][3] and earned a Ph.D. at the University of California in 1930, completing a dissertation titled "A study of color indices of faint stars in five selected areas in the Milky Way" under advisor Robert J.

[4] In 1932, she joined Annie Jump Cannon, Margaret Harwood, and Vibert Douglas in studying a solar eclipse at different locations across New England and Canada.

"Miss Slocum has been working arduously with the other scientists at the delicate job of adjusting and checking the elaborate instruments which are to be focused on the sun at the time of the eclipse," reported the Boston Globe.

[13] Publications by Slocum included "Occultations of the Pleiades by the moon on February 14, 1932" (Astronomical Journal 1932),[14] and "The eclipsing binary WW Aurigae" (Lick Observatory Bulletin 1942).

[9] In 1967, an endowment from her mother's estate established the annual Lois T. Slocum Lecture at Wilson College, named in her memory.