Gamma Sigma Delta began as a professional agricultural fraternity called Delta Theta Sigma at The Ohio State University, December 1, 1905, and maintained a chapter house.
Other chapters were installed at Iowa State (1907), Pennsylvania State College (1908), University of Missouri (1908), Oregon State College (1909), and Utah State College (1909), but all of these chapters adhered to an honorary plan and did not have chapter houses.
In 1913 Delta Theta Sigma at The Ohio State University, withdrew, maintained the name, and its chapter house. The name of the remaining organization was changed to Gamma Sigma Delta and followed the honorary plan of operation. Later (1928) a chapter of Gamma Sigma Delta was installed at Ohio State.
In 1915, the Honor Society of Agriculture was formed at the University of Minnesota. A movement was started early in 1916 to merge the two organizations, Gamma Sigma Delta and Honor Society of Agriculture. A joint committee from both organizations met at the University of Minnesota, June 3, 1916, and reached tentative agreement on the merger. Anew constitution was drafted and ratified early in 1917.
The Honor Society of Agriculture, Gamma Sigma Delta, became the official name. From 1917, Gamma Sigma Delta has been strictly honorary. It became faculty governed and selected membership from juniors, seniors, graduate students, alumni, and faculty. Currently 52 chapters have been installed at universities throughout the United States, Puerto Rico, the Philippines, and Honduras.