Society for Individual Liberty (SIL) was founded in1969 by Don Ernsberger and Dave Walter, who became its directors, after libertarian activists were expelled or later defected from Young Americans for Freedom (YAF) during and after their 1969 convention in St. Louis, Missouri. The founding of SIL is considered the defining moment that witnessed the “birth of an autonomous libertarian movement.” Purged or disillusioned YAF chapters and members withdrew from YAF and joined SIL which claimed to have 3,000 members that had grown to 103 campus chapters in the United States, “two in Canada and one each in Sweden, India and Australia” by 1970.
In 1989 SIL merged with Libertarian International under leadership of Vincent Miller, who assumed the position of president, changing the name of the organization to the International Society for Individual Liberty (ISIL) which had members in over 80 nations and hosted annual educational conference across the globe. ISIL acquired ownership of Laissez Faire Books (LFB) in November 2007. In 2016, ISIL was reorganized and renamed Liberty International with Jim Elwood serving as its executive director.
During the August 1969 YAF convention, traditionalists (trads) and libertarians (libs or rads) fought for control of the student organization. The libertarian faction lost. During the struggle and aftermath, the Anarcho-Libertarian Alliance, YAF Libertarian Caucus and two anarchist chapters of Students for a Democratic Society (SDS) worked together, and eventually organized into a loosely knit association that became known as SIL. The factional infighting came to a climax when a libertarian YAF member held up his draft card and lit it on fire on the convention floor, causing a 30 minutes fracas of punching, shoving and hostility, which lead to membership purges of many libertarian leaders, including Karl Hess, hitting the California delegation especially hard, which included Dana Rohrabacher, William B. Steel, Ron Kimberling, Rod Manis, Pat Dowd, and John Schureman, while revoking the active status of twenty-six YAF chapters. Don Ernsberger resigned from YAF, promised to continue working with SDS at Penn State and established an SIL headquarters in Philadelphia. The SIL was considered officially established by October 1969 when the Libertarian Caucus of YAF merged with Jarret Wollstein’s Society for Rational Individualism (SRI), which had been a Randian organization based in Maryland It was the influence of Roy A. Childs, Jr. who prompted the SRI to favor “anarcho-capitalism,” which later facilitated the merge with SIL. Although SIL encompassed a diversity of minarchists and anarchist libertarians, the organization adopted a black flag within a dollar sign to become its official symbol.