Mary Fels used her wealth and her talents as a writer and editor to further the Zionist cause, arguing passionately for a Jewish state and helping create both settlements and industry in Israel. Both Fels and her husband, a successful soap manufacturer, felt their wealth gave them a responsibility to reform capitalism and use their money for philanthropy. After her husband died in 1914, Fels wrote a biography of him, Joseph Fels: His Life-Work, outlining their shared values. She served as editor of The Public: A Journal of Democracy from 1917–1919, writing editorials supporting labor rights, women’s suffrage, and civil rights, as well as her belief that Palestine should be given to the Jews. She established the Joseph Fels Foundation to educate both Jews and non-Jews on the history of Israel and the importance of a Jewish homeland. In the 1920s she served as vice president of B’nai Benjamin, an organization of farmers in Palestine. Fels also continued her husband’s support for financial reform through a single tax system based on land values, and supported public land use by funding the Vacant Lot Cultivation Society, which helped establish school gardens.