The idea for a publication dedicated to homosexuals emerged from a Mattachine Society discussion meeting held on October 15, 1952. ONE Magazine’s first editors included founders of Mattachine Society and also The Knights of the Clock, a support group for interracial gay couples that had begun in Los Angeles in 1950.
ONE Inc.’s Articles of Incorporation were signed on Nov. 15, 1952 and were signed by “Tony Sanchez” (a pseudonym), Martin Block, and Dale Jennings. Other founders were Merton Bird, W. Dorr Legg, Don Slater, and Chuck Rowland. Jennings and Rowland were also Mattachine Society founders.
In January 1953 ONE, Inc. began publishing ONE Magazine, the first U.S. pro-gay publication, and sold it openly on the streets of Los Angeles. In October 1954 the U.S. Postal Service declared the magazine 'obscene'. ONE sued, and finally won in 1958, as part of the landmark First Amendment case, Roth v. United States. The magazine continued until 1967.
ONE also published ONE Institute Quarterly (now the Journal of Homosexuality). It began to run symposia, and contributed greatly to scholarship on the subject of same-sex love (then called 'homophile studies').
ONE readily admitted women, and Joan Corbin (as Eve Elloree), Irma Wolf (as Ann Carrl Reid), Stella Rush (as Sten Russell), Helen Sandoz (as Helen Sanders), and Betty Perdue (as Geraldine Jackson) were vital to its early success. ONE and Mattachine in turn provided vital help to the Daughters of Bilitis in the launching of their newsletter The Ladder in 1956. The Daughters of Bilitis was the counterpart lesbian organisation to the Mattachine Society, and the organisations worked together on some campaigns and ran lecture-series. Bilitis came under attack in the early 1970s for 'siding' with Mattachine and ONE, rather than with the new separatist feminists.
In 1965, ONE separated over irreconcilable differences between ONE’s business manager Dorr Legg and ONE Magazine editor Don Slater. After a two-year court battle, Dorr Legg’s faction retained the name “ONE, Inc.” and Don Slater’s faction retained most of the corporate library and archives. In 1968, Slater’s faction became the Homosexual Information Center or HIC, a non-profit corporation that survives today.
In 1996, ONE, Inc. merged with ISHR, the Institute for the Study of Human Resources, a non-profit organization created by transgendered philanthropist Reed Erickson, with ISHR being the surviving organization and ONE being the merging corporation. In 2005, the HIC donated many of its historic materials, including most of ONE Incorporated’s Blanche M. Baker Memorial Library, to the Vern and Bonnie Bullough Collection on Sex and Gender, a special collection within Oviatt Library at California State University, Northridge.