The Grand Chapter is an assembly of delegates composed of representatives from each Collegiate Chapter, each Alumni Chapter, the National Alumni Association and the members of the National Council. The Grand Chapter is described in National Constitution Article V, Section 2 as the supreme governing body of Phi Sigma Pi: "All final legislative powers of Phi Sigma Pi shall be vested in the Grand Chapter." The Grand Chapter is required to meet "at least once every two (2) years" (NC AXIII, S1), but traditionally meets annually during the summer months at the Grand Chapter Conference.
In 1922, amendments to the National Constitution created the Biennial Conclave of the Grand Chapter. The Conclave would bring the fraternity together every two years to conduct business. This was later changed to become an annual occurrence.
The National Constitution in Article V: Grand Chapter, Section 1 states "The Grand Chapter shall be an assembly of delegates comprised of the National Officers, representatives of each Collegiate Chapter, representatives of each Alumni Chapter, and representatives of the National Alumni Association."
The 2007 Grand Chapter approved a Constitutional amendment to establish two at-large NAA delegate and alternate positions. These delegates are granted the same rights as the Alumni Chapter delegates.
The 2009 Grand Chapter approved a Constitutional amendment to grant Alumni delegates from Alumni Chapters and the National Alumni Association full voting rights.