Sigma Tau Gamma (ΣΤΓ), commonly known as Sig Tau, is a United States college social fraternity founded on June 28, 1920, at the University of Central Missouri (then known as Central Missouri State Teachers College). The fraternity was founded as a result of friendships made while some of the founders fought in World War I in France.
 The fraternity went on to create new chapters on the campuses surrounding teachers' colleges (at the time also called "normal schools"). Since the Fraternity's beginnings in 1920, they have since spread to more than 193 university campuses across the United States.
 Sigma Tau Gamma Fraternity is an active member of the North American Interfraternity Conference.
 Four of the founders (Emmett Ellis, Leland Thornton Hoback, Edward George Grannert, and William Glenn Parsons) had enlisted and served their country together during the First World War in France. Parsons commented that in founding the Fraternity they wanted to sustain a "sense of service, responsibility, and affection for their companions."[citation needed] These four, together with Allen Ross Nieman, Edward Henry McCune, Carl Nelson Chapman, Buell Wright McDaniel, George Eugene Hartrick, A. Barney Cott, Chiles Edward Hoffman, Rodney Edward Herndon, William Edward Billings, Clarence Willard Salter, Frank H. Gorman, Alpheus Oliphant Fisher, and Daniel Frank Fisher, were the 17 founders of the fraternity.
 Several of the founders were members of the Irving Literary Society, but they wanted to create a new fraternity including members of other literary societies. On the morning of June 28, 1920, "at an unusually early hour" according to the original minutes, a list containing the names of about thirty men was posted on the college bulletin board by Emmett Ellis with a request to meet that afternoon.
 According to the minutes, "the notice had the proper effect and, as requested, there appeared a goodly number of men to learn what was in store for them." Founder Nieman, who had become familiar with fraternities while attending William Jewell College, was the principal organizer of the meeting. He explained the purpose of the meeting and told them what such an organization could mean to the men of the college. The men elected Leland Hoback temporary Chairman and Emmett Ellis temporary Secretary. They agreed to begin crafting the organization and adjourned until July 7, 1920.
 The founders were accompanied by Dr. Wilson C. Morris to present their petition to the faculty, who had been part of Sigma Nu in his college days. Dr. Morris became the Fraternity's first honorary member and served the alpha chapter at Central Missouri as patron, counselor, and advisor until he died in 1947.
 A further fourteen members were added in the first year of the fraternity's existence. Founder Edward H. McCune recalled later that, "from the very beginning, Sigma Tau Gamma prospered, both in membership and service. Its challenge to students to live well and promote the spirit of brotherhood was continually being met by those who were seeking membership."
 There are several public and private ceremonies and rituals in the fraternity, from initiation to memorials for deceased fraternity members. Sigma Tau Gamma also has a development program known as the "Path of Principles". The first eight weeks of the program challenge associate members to "promote the highest ideals of brotherhood and demonstrate an abiding spirit in which all things in life are done and possible". Content is covered during weekly associate meetings held separate from the chapter meeting.
 The fraternity's colors are azure blue, white, red, and yellow. Its mascot is the knight and its flower is the white rose.
 Its coat of arms was adopted in 1927 and modified in 1954.  The badge, which all members may purchase and wear, is the principal symbol of membership. The badge was adopted in 1927 and modified in 2016. The standard gold badge is provided to each new member at initiation. The associate pin is worn by associate members of the fraternity until initiation. The associate pin is the chapter's property and is returned to the chapter at the time of initiation by the new member.
 The fraternity hosts multiple annual events, including:
 On June 30, 2011, the Board of Directors announced its partnership with the Special Olympics in 2011, making it the fraternity’s official philanthropy. Each chapter is expected to provide service or funds directly to the Special Olympics.
 
The fraternity offers scholarships and awards to undergraduates and alumni during the summer convention. The individual awards include the Michael J. Steinbeck Fellowship, which offers assistance in the pursuit of graduate and professional degrees. Chapter awards include the Earl A. Webb Most Improved Chapter Award and the Emmett Ellis Chapter Scholarship Award Established in 1966, the Sigma Tau Gamma Foundation is its distinct legal entity, considered a public charity (501c3) by the federal government and is separate from the Sigma Tau Gamma Fraternity. It makes use of tax-deductible charitable gift dollars for the development of chapters of the Sigma Tau Gamma fraternity. The Sigma Tau Gamma Foundation started "Books for Kids" which raises money and books for public libraries and school districts.
 Established in 2014, the WPN National Housing Company is a limited liability company established to provide housing assistance and management as it relates to the housing or other forms of shared fraternity living/meeting space for undergraduate members of Sigma Tau Gamma.