A story of transgression in the face of religious ideology, a sexist scientific establishment, and political resistance to securing women's right to vote. When Ohio newspapers published the story of Alice Chenoweth's affair with a married man, she changed her name to Helen Hamilton Gardener, moved to New York, and devoted her life to championing women's rights and decrying the sexual double standard. She published seven books and countless essays, hobnobbed with the most interesting thinkers of her era, and was celebrated for her audacious ideas and keen wit. Opposed to piety, temperance, and conventional thinking, Gardener eventually settled in Washington, D.C., where her tireless work proved, according to her colleague Maud Wood Park, "the most potent factor" in the passage of the Nineteenth Amendment. Free Thinker is the first biography of Helen Hamilton Gardener, who died as the highest-ranking woman in federal government and a national symbol of female citizenship. Hamlin exposes the racism that underpinned the women's suffrage movement and the contradictions of Gardener's politics. Her life sheds new light on why it was not until the passage of the 1965 Voting Rights Act that the Nineteenth Amendment became a reality for all women. Celebrated in her own time but lost to history in ours, Gardener was hailed as the "Harriet Beecher Stowe of Fallen Women." Free Thinker is the story of a woman whose struggles, both personal and political, resound in today's fight for gender and sexual equity.