Delta Chi (ΔΧ) (del-ta kai) or D-Chi is an international Greek letter college social fraternity formed on October 13, 1890, at Cornell University, initially as a professional fraternity for law students. On April 29, 1922, Delta Chi became a general membership social fraternity, eliminating the requirement for men to be studying law, and opening membership to all areas of study. On April 22, 1929 Delta Chi became the first international fraternity to abolish "hell week". Delta Chi is a charter member of the North-American Interfraternity Conference (NIC). The Fraternity is headquartered at 314 Church Street in Iowa City, Iowa 52244. As of Spring 2011, Delta Chi has initiated over 106,000 members.

Two incidents have been credited with providing the impetus for interest in the founding of what was to become Delta Chi. One was the election of a Phi Delta Phi as the Law School Editor of the Cornell Daily Sun (the student newspaper) and the second was the election of the law school junior class president. In the case of the class presidency, Alphonse Derwin Stillman had done some campaigning for a student named Iving G. Hubbs and was unaware of any effort being made on anyone else’s behalf. When the voting results were in, Charles Frenkel, a Phi Delta Phi, was declared the winner. Frustrated, Stillman began to ask around about the election. What he found was a law school that was dominated by one small, close-knit group—Phi Delta Phi.

Delta commonly refers to:

Delta may also refer to:

Along with the aforementioned Delta Airlines, other companies named Delta include:

, an inverted delta representing del, a vector differential operator

, the Kronecker delta function

, the Dirac delta function

Chi may refer to:

CHI may stand for: