(1860–1945) Completed the first major study on women's sexuality, Factors in the Sex Lives of Twenty-Two Hundred Women, which was published in 1929. She gathered data for more than 10 years about the sex lives of middle-class women. Also worked with sex workers in prison. She looked at sexual desire, masturbation, frequency of intercourse, use of birth control, marriage, sources of sexual instruction and information, and same-sex intimate relationships. Her study challenged the narrow reproductive view of women's sexuality that was common at the beginning of the 20th century. It was our first real glimpse into the sex lives of real women.