The National Panhellenic Conference (NPC) is an umbrella or trade association for 26 national and international women's sororities throughout the United States and Canada. Panhellenic (lit. 'all-Greek') refers to the group's members being autonomous social Greek-letter societies of college women and alumnae.

The National Panhellenic Conference provides guidelines and resources for its members and serves as a national voice on contemporary issues of sorority life. Founded in 1902, the NPC is one of the oldest and largest women's membership organizations, representing more than four million women at over 650 college and university campuses and 4,600 local alumnae chapters in the U.S. and Canada. Each year, NPC-affiliated collegians and alumnae donate more than $5 million to causes, provide $2.8 million in scholarships to women, and volunteer 500,000 hours in their communities.

The organization is a conference, not a congress, as it enacts no legislation and only regulates its own meetings. Other than basic agreements which its member groups must unanimously vote to follow, the NPC confines itself to recommendations and advice and acts as a court of final appeal in any college Panhellenic disputes. One of its services is providing advisors for sororities.

Early histories of sororities contain accounts of rushing and pledging agreements or compacts among sororities on various campuses, and many stories of cooperation and mutual assistance. However, no actual Panhellenic organization existed and no uniform practices were observed. The NPC's origin can be traced to 1891, when Kappa Kappa Gamma invited all seven existing sororities to a Boston meeting, with the intention to meet again in 1893.

In 1902, Alpha Phi invited Pi Beta Phi, Kappa Alpha Theta, Kappa Kappa Gamma, Delta Gamma, Gamma Phi Beta, Delta Delta Delta, Alpha Chi Omega, and Chi Omega to a conference in Chicago on May 24 to set standards for collegiate sororities. Alpha Chi Omega and Chi Omega were unable to attend and joined the following year. The remaining seven groups met and the session resulted in the organization of the Inter-Sorority Conference, the first interfraternity association and the first intergroup organization on college campuses. The first few meetings resulted in several mutual agreements, especially regarding pledging. Up to this time, no guidelines had been set, and women could be pledged to groups before enrolling in college and belong to more than one group. It became the National Panhellenic Conference in 1908 and the National Panhellenic Congress in 1911.

Many sororities joined through the next decade, with Alpha Xi Delta in 1904, Alpha Omicron Pi and Sigma Kappa in 1905, Alpha Delta Pi and Alpha Gamma Delta and Zeta Tau Alpha in 1909, Delta Zeta in 1910, Phi Mu in 1911, and Kappa Delta in 1912. No new member organizations were admitted for the next few decades.

Throughout its early years, NPC members were often racially and religiously segregated and rarely admitted Jewish, Catholic, or ethnic minority members, which led to the formation of group-specific sororities which attempted to provide the same social and academic outlets to groups who were otherwise excluded from membership. These groups included the first Black Greek letter organizations.

In 1917, it changed back to the National Panhellenic Conference, only to return to the National Panhellenic Congress name in 1921. By 1922, the NPC had an executive committee consisting of a chairman, secretary, and treasurer; a publicity board; and a delegate board with at least one representative from each of its eighteen senior members. That year, the congress also began plans for a centralized headquarters to coordinate and streamline interactions with the separate sororities.