Mary McHenry Keith (1855–1947) was an American lawyer and social justice advocate who was especially known for her work in the woman suffrage and animal rights movements.

[5] As of result of the activist work of Clara Shortridge Foltz and Laura de Force Gordon, the newly formed University of California's Hastings Law School began admitting female students just as McHenry completed her undergraduate degree.

[7][8][3][9] Upon her marriage to prominent landscape artist William Keith in 1883, Mary stopped practicing law and focused her attention on activist causes, most especially women's and animal rights issues.

As a college student, Mary McHenry is reported to have been part of the dress reform movement, drawing attention to the ways in which a woman's clothing restricted her abilities to comfortably and effectively engage in the full range of activities available to her male classmates.

[10] After marrying and giving up her law practice, Mary McHenry Keith was able to devote more time to activism including promoting woman suffrage and opposing white slavery and prostitution.

[9][12] With a membership of over 200, the Berkeley Political Equality Club was one of the largest suffrage organizations in California and throughout the West Coast of the US.

[12] As a component of this work, Keith intentionally sought the support of influential women and men who could lend their voices and finances to the cause.

Keith supported suffrage for a variety of reasons including personal empowerment and social reform, identifying its value to the common good as well as the individual.

[10] Even so, recognizing some of the opposition to overly-independent women, Keith and other leaders in the suffrage movement primarily emphasized altruistic purposes over individual benefits when engaged in public speaking.

Concerns about coeducation and women's increasing enrollments in high schools and colleges were issues Keith discussed with both Elizabeth Cady Stanton and Susan B. Anthony, as prominent male university and government leaders were lamenting the impacts on men and society of women's expanded educational participation.

The proposal was not supported, but the text of the letter was preserved and reads in part,We ... hereby commit the cause of Equal Suffrage for man and woman to the judgment of future generations, in the confidence that in after years whoever shall read these lines will wonder that so late as the year 1908 the women of California were political serfs; they were taxed without representation, governed without their consent, and classed under the law with idiots, insane persons, criminals, minors and other defective classes ... We, about to die, greet you, the inheritors of a better age, men and women of the future Berkeley, equal before the law, enfranchised citizens; co-operating in all public service.Keith's prominence as not only a local, but national, figure in the suffrage movement is demonstrated by her inclusion in the program of the 60th Anniversary Celebration of the Seneca Falls Convention, held October 15–21, 1908 in Buffalo, NY.

In addition to some of the original convention attendees, the anniversary celebration included Mary Keith, Jane Addams, Alice Stone Blackwell, Harriet May Mills, Cary Thomas, Dorothy Dix, and Rev Antoinette Brown.

[17] Although she often got to speak to audiences who were supportive of woman suffrage, she was also concerned by the number of people, especially women, who remained uncommitted or indifferent to the cause and needed to be slowly and cautiously convinced of its necessity.