Bloomers, also called the bloomer, the Turkish dress, the American dress, or simply reform dress, are divided women's garments for the lower body. They were developed in the 19th century as a healthful and comfortable alternative to the heavy, constricting dresses worn by American women. They take their name from their best-known advocate, the women's rights activist Amelia Bloomer.

The name "bloomers" was derogatory and was not used by the women who wore them, who referred to their clothes as the "Reform Costume" or the "American Dress."

Bloomers were an innovation of readers of the Water-Cure Journal, a popular health periodical that in October 1849 began urging women to develop a style of dress that was not so harmful to their health as the existing fashion. It also represented an unrestricted movement, unlike previous women's fashions of the time, that allowed for greater freedom—both metaphorical and physical—within the public sphere. The fashionable dress of that time consisted of a skirt that dragged several inches on the floor, worn over layers of starched petticoats stiffened with straw or horsehair sewn into the hems. In addition to the heavy skirts, prevailing fashion called for a "long waist" effect, achieved with a whale-bone-fitted corset.

Women responded with a variety of costumes, many inspired by the pantaloons of Turkey, and all including some form of pants. By the summer of 1850, various versions of a short skirt and trousers, or "Turkish dress", were being worn by readers of the Water-Cure Journal as well as women patients at the nation's health resorts. After wearing the style in private, some began wearing it in public. In the winter and spring of 1851, newspapers across the country carried startled sightings of the dresses.

The wearing of bloomers—a woman wearing pants, a men's garment—was a question of power. The symbolism of bloomers was enormous. Men felt threatened by them, and sometimes disparaged women wearing them as "Amazons" or "male impersonators".

In February 1851, Elizabeth Smith Miller of Peterboro, New York, wore the "Turkish dress" to the Seneca Falls, New York, home of Amelia Bloomer and her temperance journal, The Lily. The next month, Bloomer announced to her readers that she had adopted the dress and, in response to many inquiries, printed a description of her dress and instructions on how to make it. Her circulation rose from 500 to 3,000. By June, many newspapers had dubbed it the "Bloomer dress".

During the summer of 1851, the nation was seized by a "bloomer craze". Health reformer Mary Gove Nichols drafted a Declaration of Independence from the Despotism of Parisian Fashion and gathered signatures to it at lectures on woman's dress. Managers of the textile mills in Lowell, Massachusetts, gave a banquet for any of their female workers who adopted the safer dress before July 4. In Toledo, Ohio, 60 women turned out in Turkish costume at one of the city's grandest social events. Bloomer balls and bloomer picnics were held; dress reform societies and bloomer institutes were formed. A grand festival in favor of the costume was held at New York City's Broadway Tabernacle in September. In August, a woman who had spent six months sailing from Philadelphia around the Horn to California with the reform dress packed in her trunk disembarked to find that the dress had preceded her and was being displayed in the window of a San Francisco dress shop.

Interest in the bloomers was also sparked in England when Hannah Tracy Cutler and other women delegates wore the new dress to an International Peace Congress in London. Many newspaper reports were dedicated to the controversy the outfit caused. One prominent figure who began to lecture about the bloomers in London and beyond was Caroline Dexter. When she and her husband later emigrated to Australia, she continued to advocate for dress reform. Although few women are known to have worn the bloomers in Australia, Dexter's continued support led to controversy in The Sydney Morning Herald.