Using periodicals, catalogs, extant garments, postcards, patents, photographs, and newspapers, I traced the origin and development of women's functional swimwear from the bloomer costume of the 1850s to the "tank suit" of the 1920s. To gain insight into exogenous or external forces that may influence the fashion process, I considered urban lifestyle, education and status of women, leisure activities, swimming facilities, renowned swimmers, the Olympics, knit technology, water travel, drownings, life preservers, and public baths;Initial findings supported the thesis that women's bathing garments followed the dominant outerwear silhouette of the era. Visual data indicated women generally adopted the tank suit by 1915, while men and children adopted the style much earlier. However, descriptive data indicated that some women had also adopted this style earlier. Moreover, I found that women swam much earlier than generally assumed; that various functional attire was sanctioned for women engaged in exhibitions, competitions, teaching, and bathing at the bathhouses; and that many male swimmers encouraged and taught female relatives to swim;Many factors had an impact on functional swimwear, but I contend the public bath movement was the greatest influence. When people moved to the cities for employment, they lived in boarding houses with limited access to water for cleansing purposes. By the 1870s free public bathhouses were established to curb disease, assimilate immigrants, improve morality, and meet middle-class standards of cleanliness. Although intended for the poor, the baths were regularly patronized by young working women, school girls, mothers with babies, and upper-class "ladies" on the days reserved solely for women. In the large "swimming baths," female supervisors taught patrons of all ages and physical ability to swim. Since much transportation and leisure relied on water, swimming offered some insurance against drowning, a common occurrence;Bath patrons were required to wear simple, non-skirted swim suits. By 1900, thousands of women learned to swim in these garments. By 1915, when the public baths were no longer needed, women wore functional swimwear in public. While first associated with the poor, the style was legitimized by prominent women and "trickled-up" to the majority of U.S. women.