The following is a list of Rensselaer Polytechnic Institute fraternities and sororities. In 2016, the university ranked number fifteen on a list of the "frattiest" colleges in America, with thirty percent of its male students belonging to one of its 29 fraternities. As of the fall of 2023, that number had declined to sixteen percent of male undergraduates belonging to a fraternity and eleven percent of female undergraduates belonging to a sorority.
As of 2024, Rensselaer Polytechnic Institute's Fraternity & Sorority Commons (FSC) community includes four distinct clusters: the Interfraternity Council (IFC) with 23 active fraternities; the Multicultural Sorority & Fraternity Council (MSFC) with one sorority and three fraternities; the Rensselaer Panhellenic Council (RPC) with three sororities; and the Professional Fraternity/Sorority cluster with one fraternity and one sorority. The FSC is also working with several intercultural fraternities/sororities and NIC fraternities on their respective reactivation statuses.
Active fraternities The governing body of all fraternities is the Inter-Fraternity Council.
Acacia, founded on April 10, 1949 Alpha Chi Rho (; Crows), Delta Phi chapter, founded on October 23, 1948 Alpha Epsilon Pi (ΑΕΠ), Rho Pi chapter, founded in 1951 Alpha Phi Alpha () Alpha Phi Omega (), Epsilon Zeta chapter (co-ed, not in IFC), founded on May 11, 1947 Serves as RPI's premier co-ed service fraternity. APO runs various campus-wide services out of their office on the third floor of the Student Union including Lost & Found, back exams, loaner technology, and information cards. Alpha Sigma Phi (; A-Sig), Beta Psi chapter founded in 1946. Alpha Sigma Phi was founded on December 6, 1845, at Yale College by Louis Manigault, Stephen Ormsby Rhea, and Horace Spangler Weiser. It was founded “to Better the Man through the creation and perpetuation of brotherhood founded upon the values of Character, Silence, Charity, Purity, Honor, and Patriotism.” The history of the Beta Psi chapter of Alpha Sigma Phi can be traced back to the founding of the Lambda chapter of Theta Nu Epsilon in 1882. Due to financial constraints from the Great Depression and dwindling numbers in membership, it merged with the Alpha Kappa chapter of Alpha Kappa Pi in 1940. After World War 2, Alpha Kappa Pi across the entire nation faced more trouble with membership and would finally merge with Alpha Sigma Phi in 1946, when the chapter at RPI became the Beta Psi chapter. The fraternity’s membership would be at stake again as the United States entered the Vietnam War, but the Beta Psi chapter would face its biggest challenge following its suspension from RPI and the National Organization in the 1990’s. This era of difficulty led to low membership. In local tradition and oral history, the brothers primarily responsible for the fraternity's resurgence were Jason Stern, Paul Lambeck, and Adam "Digby" Wells. The efforts of these three brothers are considered critically important to maintaining the chapter's traditions and ensuring its continued presence on RPI's campus. This is considered the re-founding of the Beta Psi chapter and is symbolic of Alpha Sigma Phi’s national symbol, the phoenix. Today, the lineage of all active brothers can be traced back to Stern and Lambeck. The Beta Psi chapter of Alpha Sigma Phi maintains a membership of approximately twenty brothers. The current chapter house is on 16 Belle Ave in Troy, NY. The house can act as a place where active brothers can choose to live in, host brotherhood events, and hold chapter meetings. The house is frequently visited by alumni and other friends of the house. The chapter is part of the Inter-Fraternity Council (IFC) on campus and remains in contact with the National Chapter of Alpha Sigma Phi. Additionally, the Beta Psi chapter also plans an annual 24-Hour Extra Life charity stream around the time of November to raise money for children’s hospitals.
Chi Phi (), Theta chapter, founded in 1878. Theta chapter of Chi Phi is one of the oldest fraternities on campus and owns two houses next door to each other at 1981 and 1985 15th St., across from the Quad and Student Union. The Chi Phi house at 1981 15th Street was constructed in 1912 and is the oldest continually occupied fraternity house on RPI's campus. Notable alumni from Chi Phi at RPI include George Washington Gale Ferris Jr., inventor of the Ferris wheel, and Frank Osborn, founder of Osborn Engineering and designer of the original Yankee Stadium, Tiger Stadium, and Fenway Park. Chi Phi organizes the annual St. Baldrick's Foundation fundraiser for pediatric cancer research on RPI's campus that continually raises over $20,000 every year. Delta Kappa Epsilon (; Dekes), founded in 1867. DKE used to own the current admissions building located next to Theta Xi and across from both RSE and the Student Union. Delta Phi (), Lambda chapter, founded in 1864. Lambda chapter of Delta Phi is rich in Rensselaer history. Its members include three Rensselaer presidents (including George Low, known for putting the first man on the moon), and there are about sixteen structures on campus named after Delta Phi alumni. Such buildings include the George M. Low Building, Livingston Houston Fieldhouse, Cornelius Barton Hall, Nason Hall, Mason Lab (no longer in existence), Hearne Dormitory, Church I-VI and Caldwell Lab. Their chapter house is located at 311 Congress St. in Troy, NY, and is nicknamed "The Academy." Delta Tau Delta (; Delts), Upsilon chapter, founded in 1879. Upsilon chapter of Delta Tau Delta is located at 133 Sunset Terrace, neighboring Acacia and Phi Kappa Theta. The Delts' house is one of the largest on campus. Lambda Chi Alpha (), Epsilon Eta chapter, founded in 1937. Located at 200 Sunset Terrace. Formerly Delta Sigma Lambda, a local fraternity that was rechartered as Lambda Chi Alpha.. Phi Gamma Delta (; FIJI), Tau Nu chapter, founded in 1984. Located at 82 3rd Street in Downtown Troy. Their house is the iconic 1st Baptist Church in Troy. They are the second fraternity to ever live in a church. Phi Iota Alpha (; Phiotas), Alpha chapter, founded on December 26, 1931. The Union Hispano-Americana was founded at RPI. It is the Oldest Hispanic-American student organization in the United States. The Latin American fraternity, Pi Delta Phi Fraternity, was founded at the Massachusetts Institute of Technology. It became Phi Lambda Alpha after merging with Union Hispano Americana at RPI in 1919. Phi Lambda Alpha became Phi Iota Alpha Fraternity in 1931. Delegates from Phi Lambda Alpha Fraternity (at RPI/Berkeley/MIT) and Sigma Iota Fraternity (Louisiana State) assembled at Troy, NY to form a strong and extensive Fraternity to address the needs of Latin Americans in universities in the US. It was then that Phi Iota Alpha was created. Today, the Fraternity has over 40 chapters. Phi Kappa Theta (; Ski Lodge), Sigma chapter, founded in 1925. The current house was designed by brother Robert Trudeau in 1971. It will always be the home of Apres Ski. Phi Mu Delta (; Phi Mud), Nu Theta chapter, founded in 1929 Phi Sigma Kappa (; Phi Sig or Church), Gamma Tetarton chapter, founded October 14, 1950. Located at 316 Congress Street, at the corner of Congress Street and 13th Street, the Gamma Tetarton chapter of Phi Sigma Kappa is also the very first fraternity in the country to ever purchase and live in a church. Their house is one of the largest fraternity houses in the country, and is also the physically largest fraternity house on campus. The house was formerly the iconic St. Francis DeSales Church, which closed on February 1, 2009. The Gamma Tetarton chapter completed the purchase of the St. Francis DeSales Church on February 4, 2011. Shortly after their move-in, Phi Sig began the Mt. Ida Community Microgrant program. As neighbors dedicated to the growth, improvement, and future of the Mt. Ida community, Phi Sig sponsors the grant program to improve the “quality of life” in the Mt. Ida neighborhood. Homeowners, landlords, business owners, and non-profits are eligible to apply for a grant of up to the amount of $1,000 for home improvement, historic restoration, neighborhood beautification projects, and more. Pi Delta Psi (), Theta chapter, founded in 1997. Pi Delta Psi is currently the only Asian-interest Greek organization on campus. Pi Kappa Alpha (; Pikes) Pi Kappa Phi (; Pi Kapp or locally as Castle), Alpha Tau chapter, founded in 1906. Originally the local Fraternity, "The Rensselaer Technical Society", the chapter was incorporated in 1909 and rechartered in 1931 to form the Alpha Tau chapter of the national fraternity Pi Kappa Phi. Pi Kappa Phi "Castle" is located in its long-time home in the Central Troy Historic District, the Paine Mansion, where its castle-like façade and opulent interior gives the fraternity its nickname. The Paine Mansion finished construction in 1896 and is located at 49 2nd Street. Pi Lambda Phi (; Pilam), founded in 1954 Psi Upsilon (; Psi U), Epsilon Iota chapter, founded on April 16, 1982. Originally the Epsilon Iota chapter of Tau Epsilon Phi() Fraternity, the chapter officially seceded from TEP in January 1978 to become a co-ed local fraternity. Epsilon Iota officially became the 37th chapter of the Psi Upsilon international fraternity on April 16, 1982, and remains co-ed with an approximately equal number of male and female brothers. The chapter currently resides at 2140 Burdett Avenue in Troy. The chapter holds the record for the longest number of days (178) in "hockey line" at RPI, breaking the previous record of 33 days. Rensselaer Society of Engineering Innovation (RSEi), formally referred to locally as ‘’’Rensselaer Society of Engineers (RSE), founded 1866. Located at 1501 Sage Avenue. The Rensselaer Society of Engineers was founded as the Pi Eta scientific society in 1866, becoming the Rensselaer Society of Engineers in 1883. At 150 years old RSE is the oldest independent local fraternity at RPI. There are no other chapters. RSE's 1924 building is on the National Register of Historic Places. Sigma Chi () Delta Psi chapter, founded on December 2, 1950. The Delta Psi chapter of The Sigma Chi Fraternity was chartered on December 2, 1950. Before that, Sigma Chi existed on the RPI campus as a local fraternity known as Phi Epsilon Phi. Sigma Chi is currently located at 58 Pinewoods Avenue. Sigma Alpha Epsilon (; SAE), New York Epsilon chapter, founded on December 8, 1951. The New York Epsilon chapter of Sigma Alpha Epsilon began as a local chapter in 1948, known as Lambda Alpha Epsilon, before being officially designated as Sigma Alpha Epsilon in 1951. The chapter received the 'Epsilon' designation in recognition of the chapter's founder, Forrest K. English '51. The chapter house was originally located at 7 Hawthorne Avenue before relocation to 12 Myrtle Avenue, which is known as the Thomson Mansion, and the former residence of Saul Chuckrow, former chicken magnate of Troy. Sigma Alpha Epsilon has remained at 12 Myrtle Avenue ever since. Sigma Phi Epsilon (; SigEp), New York Delta chapter, founded in 1938. Located at 2005 15th Street. Tau Epsilon Phi (; TEP), Epsilon Iota chapter, founded on December 8, 1957. Located at 1991 15th Street.This chapter was re-established as a colony in 1988 after a brief hiatus when its original chapter opted to become a local, co-ed operation that would later accept a charter from Psi Upsilon. Tau Kappa Epsilon (; TEKE), founded at RPI as the Gamma Epsilon chapter in 1949. Located at 1661 Tibbets Avenue, Troy, NY.