The Fox sisters were three sisters from Rochester, New York who played an important role in the creation of Spiritualism: Leah (April 8, 1813 – November 1, 1890), Margaretta (also called Maggie), (October 7, 1833 – March 8, 1893) and Catherine Fox (also called Kate) (March 27, 1837 – July 2, 1892). The two younger sisters used "rappings" to convince their older sister and others that they were communicating with spirits. Their older sister then took charge of them and managed their careers for some time. They all enjoyed success as mediums for many years.

In 1888, Margaretta confessed that the rappings had been a hoax and publicly demonstrated their method. Despite their confession, the Spiritualism movement continued to grow in popularity.

In 1848, the two younger sisters—Catherine and Margaretta—lived with their parents John and Margaret, who were Methodists, in Hydesville, New York, a former hamlet that was part of the township of Arcadia in Wayne County, New York, just outside of Newark. The girls had been born and raised "in or near Consecon," a tiny village in Prince Edward County, Ontario where their father owned a farm. The family moved to Hydesville, New York, in 1847.

The house was reputed to be haunted, yet is reported to have been a prank. (The sisters claimed in 1888 that they made the sounds by cracking their knuckles and other joints as well as other means. By that time, 40 years later, the sisters were famous mediums.) Margaretta Fox, in her later years noted that neighbors were sure that the house was haunted, reputedly after a man who had been murdered in the house by a (falsely- accused) man named Bell.

Kate and Margaretta were sent to nearby Rochester during the excitement—Kate to the house of her sister Leah (now the married Leah Fox Fish), and Margaretta to the home of her brother David—and the rappings followed them. Amy and Isaac Post, a radical Quaker couple and long-standing friends of the Fox family, invited the girls into their Rochester home. Immediately convinced of the genuineness of the phenomena, they helped to spread the word among their radical Quaker friends, who became the early core of Spiritualists. In this way, the association between Spiritualism and radical political causes developed, such as abolition, temperance, and equal rights for women.

On 14 November 1849, the Fox sisters demonstrated their spiritualist rapping at the Corinthian Hall in Rochester. This was the first demonstration of spiritualism held before a paying public and inaugurated a long history of public events featured by spiritualist mediums and leaders in the United States and in other countries.

Kate and Margaretta became famous mediums and they held séances for hundreds of people. Many of these early séances were entirely frivolous, where sitters sought insight into "the state of railway stocks or the issue of love affairs."

Horace Greeley, the prominent publisher and politician, became a kind of mentor for them, enabling their movement in higher social circles. Their public séances in New York in 1850 attracted notable people, including William Cullen Bryant, George Bancroft, James Fenimore Cooper, Nathaniel Parker Willis, Sojourner Truth and William Lloyd Garrison. Although Greeley watched over the sisters, the lack of parental supervision was pernicious, as both of the young women began to drink wine.