Professional fraternities, in the North American fraternity system, are organizations whose primary purpose is to promote the interests of a particular profession and whose membership is restricted to students in that particular field of professional education or study. This may be contrasted with service fraternities and sororities, whose primary purpose is community service, and general or social fraternities and sororities, whose primary purposes are generally aimed towards some other aspect, such as the development of character, friendship, leadership, or literary ability.
Professional fraternities are often confused with honor societies because of their focus on a specific discipline. Professional fraternities are actually significantly different from honor societies in that honor societies are associations designed to provide recognition of the past achievement of those who are invited to membership. Honor society membership, in most cases, requires no period of pledging, and new candidates may be immediately inducted into membership after meeting predetermined academic criteria and paying a one-time membership fee. Because of their purpose of recognition, most honor societies will have much higher academic achievement requirements for membership.
Professional fraternities, on the other hand, work to build brotherhood among members and cultivate the strengths of members in order to promote their profession and to provide assistance to one another in their mutual areas of professional study. Membership in a professional fraternity may be the result of a pledge process, much like a social fraternity, and members are expected to remain loyal and active in the organization for life. Within their professional field of study, their membership is exclusive; however, they may initiate members who belong to other types of fraternities.
The first professional fraternity was founded at Transylvania University in Lexington, Kentucky in 1819: the Kappa Lambda Society of Aesculapius, established for the purpose of bringing together students of the medical profession. The fraternity lasted until about 1858.
Of the professional fraternities still in existence, the oldest is Phi Delta Phi founded at the University of Michigan in 1869; however, Phi Delta Phi changed its mission in 2012 to become an honor society for law school students.
Title IX applied to professional fraternities
Professional fraternities, in the United States fraternity system, are usually co-educational in accord with Federal Title IX of the Education Amendments of 1972 (commonly referred to as "Title IX"). This federal law discourages discrimination on the basis of sex in any college or university receiving federal financial assistance. However, the membership practices of social fraternities and sororities are exempt from Title IX in section (A)(6)(a). The U.S. Department of Education (DOE) regulations adopted pursuant to Title IX also allow such an exception for "the membership practices of social fraternities and sororities." (34 C.F.R. Sec. 106.14(a)).
Prior to Title IX, many professional fraternities were all male and most professional sororities/women’s fraternities were all female. Several of these professional fraternities and sororities even considered themselves both professional and social organizations because they often emphasized the social aspects of their activities. During the ensuing years since the enactment of Title IX, single-sex professional fraternities and sororities became coeducational to conform to Title IX. Several organizations simply opened their membership both men and women. For example, Phi Chi (medicine) opened membership to women in 1973; Phi Beta (music and speech) opened membership to men in 1976; and Delta Omicron (music) opened membership to men in 1979. A few single-sex groups merged with other organizations, such as Phi Delta Delta, a women’s professional law fraternity, merged with Phi Alpha Delta (law) in 1972.
Despite the fact that Title IX was enacted in 1972, there continues to be professional fraternities and sororities or their chapters that have not become coeducational and therefore, do not conform to Title IX. Generally, these groups still claim to be both professional and social organizations, for instance, Alpha Gamma Rho (men in agriculture), Alpha Omega Epsilon (women in engineering), and Sigma Phi Delta (men in engineering).
Severall social fraternities and sororities have membership practices of selecting their members primarily from students enrolled in particular majors or areas of study, including Phi Mu Alpha Sinfonia, Phi Sigma Rho, and Triangle. Nevertheless, these groups are social, rather than professional, organizations. Although they select members from students in a particular field of study, like a professional fraternity, they are single-sex social organizations because their purposes focus only on the social development of their members. Examples of groups that have been officially granted exemption from Title IX by the DOE to remain single-sex include Sigma Alpha Iota in 1981  and Phi Mu Alpha Sinfonia in 1983.
Many professional fraternities, particularly those of the highest esteem and reputation, are members of the Professional Fraternity Association (PFA). This group resulted in 1978 from a merger of the Professional Interfraternity Conference (PIC) (for men's groups) and the Professional Panhellenic Association (PPA) (for women's groups). In 2013, faced with an increase in campus policies that require student organizations to take all students, the PFA adopted a resolution against All Comers policies.
List of professional fraternities
- ΚΠ - Kappa Pi - art; co-ed international fraternity
- ΑΓΡ - Alpha Gamma Rho - agriculture; men's fraternity, not co-ed
- ΑΓΣ - Alpha Gamma Sigma - agriculture; men's fraternity, not co-ed
- ΑΖ - Alpha Zeta - agriculture; originally a men's fraternity, co-ed since 1972
- ΔΘΣ - Delta Theta Sigma - agriculture; co-ed
- ΣΑ - Sigma Alpha - agriculture; women's sorority, not co-ed by chapter
- ΑΚΨ - Alpha Kappa Psi - business; originally a men's fraternity, co-ed since 1976
- ΔΣΠ - Delta Sigma Pi - business; originally a men's fraternity, co-ed since 1975
- ΔΜΚ - Delta Mu Kappa - entrepreneurship; co-ed
- ΕΝΤ - Epsilon Nu Tau - entrepreneurship; co-ed
- ΓΙΣ - Gamma Iota Sigma - insurance, risk management, actuarial sciences; co-ed
- ΦΒΛ - Phi Beta Lambda - business; co-ed
- ΦΧΘ - Phi Chi Theta - business; originally a women's sorority, co-ed since 1976
- ΦΓΝ - Phi Gamma Nu - business; originally a women's sorority, co-ed since 1974
- ΠΣΕ - Pi Sigma Epsilon - marketing, sales; originally a men's fraternity, co-ed since 1974
- ΣΨΜ - Sigma Psi Mu - sport management; co-ed
- ΑΔΥ - Alpha Delta Upsilon - chiropractic; women's sorority
- ΧΡΣ - Chi Rho Sigma - chiropractic; co-ed
- ΔΣΧ - Delta Sigma Chi - chiropractic; men's fraternity
- ΠΚΧ - Pi Kappa Chi - chiropractic; men's fraternity
Engineering, architecture, and science
- ΑΩΕ - Alpha Omega Epsilon - engineering; women's sorority, established November 13, 1983
- ΑΡΧ - Alpha Rho Chi - architecture
- ΑΣΚ - Alpha Sigma Kappa - Women in Technical Studies (WiTS) - architecture, engineering, mathematics, and sciences; women's social sorority, established May 1, 1989
- ΚΗΚ - Kappa Eta Kappa - electrical and computer engineering
- ΦΣΡ - Phi Sigma Rho - engineering and engineering technology; women's sorority, established 1984
- ΣΦΔ - Sigma Phi Delta - engineering; men's fraternity, established April 11, 1924
- ΘΤ - Theta Tau - engineering; founded October 15, 1904, largest, oldest, and foremost fraternity for engineers
Environment and Sustainability
- ΔΘΦ - Delta Theta Phi - law;  originally a men's fraternity, co-ed since 1971
- ΚΑΠ - Kappa Alpha Pi - law; co-ed
- ΦΑΔ - Phi Alpha Delta - law; co-ed
- ΦΔΦ - Phi Delta Phi - law; co-ed, technically a legal society, but undergraduate halls are considered professional fraternities at most schools
- ΣΑΝ - Sigma Alpha Nu - law; co-ed
- ΑΚΠ - Alfa Kappa Pi - medicine; Dominican Republic and Puerto Rico
- ΑΓΚ - Alpha Gamma Kappa - podiatry; co-ed
- ΆΚΚ - Alpha Kappa Kappa - medicine
- ΑΠΥ - Alpha Pi Upsilon - pre-medical; local fraternity at Olivet College
- ΑΩ - Alpha Omega - dentistry; co-ed
- ΑΨ - Alpha Psi - veterinary medicine
- ΑΤΔ - Alpha Tau Delta - nursing; co-ed
- ΒΣΚ - Beta Sigma Kappa - optometry
- ΧΗΦ - Chi Eta Phi - nursing; primarily an African American women's sorority
- ΔΕΜ - Delta Epsilon Mu - health
- ΔΣΔ - Delta Sigma Delta - dentistry
- ΕΨΕ - Epsilon Psi Epsilon - optometry; local fraternity at Ohio State University
- ΚΓΔ - Kappa Gamma Delta - all-female pre-medical
- ΚΤΕ - Kappa Tau Epsilon - podiatry
- ΜΕΔ - Mu Epsilon Delta - health
- ��ΣΝ - Nu Sigma Nu - medicine
- ΝΡΨ - Nu Rho Psi - neuroscience
- ΩΤΣ - Omega Tau Sigma - veterinary medicine
- ΩΥΦ - Omega Upsilon Phi - medicine; defunct after Phi Beta Pi 1934 merger; Alpha Chapter joined Phi Chi
- ΦΑΓ - Phi Alpha Gamma - osteopathic medicine; merged with Phi Chi in 1948
- ΦΑΣ - Phi Alpha Sigma - medicine
- ΦΒΠ - Phi Beta Pi - medicine
- ΦΧ - Phi Chi - medicine
- ΦΔΕ - Phi Delta Epsilon - medicine
- ΦΚΜ - Phi Kappa Mu - University of the Philippines College of Medicine
- ΦΛΚ - Phi Lambda Kappa - medicine
- ΦΣΓ - Phi Sigma Gamma - men's osteopathic fraternity
- ΦΡΣ - Phi Rho Sigma - medicine
- ΠΜ - Pi Mu Honor Society - medicine; merged with Phi Chi in 1922
- ΨΩ - Psi Omega - dentistry
- ΣΜΔ - Sigma Mu Delta - all-male pre-medical
- ΣΦХ - Sigma Phi Chi - chiropractic women's sorority
- ΘΚΨ - Theta Kappa Psi - medicine
- ΞΨΦ - Xi Psi Phi - dentistry
Military, government, and foreign service
- ΑΓΞ - Alpha Gamma Xi Military Sorority, Inc.
- ΔΦΕ - Delta Phi Epsilon - Foreign Service
- ΚΕΨ - Kappa Epsilon Psi Military Sorority, Inc.
- ΚΛΧ - Kappa Lambda Chi Military Fraternity Inc.
- ΛΒΑ - Lambda Beta Alpha Military Sorority Inc.
- ΜΒΦ - Mu Beta Phi Military Fraternity Inc.
- Pershing Angels - military drill sorority
- Pershing Rifles - military drill fraternity
- Scabbard and Blade - military
- ΔΟ - Delta Omicron - music; originally a women's sorority, co-ed since 1977
- ΚΚΨ - Kappa Kappa Psi - band; originally a men's fraternity, co-ed since 1977
- ΜΒΨ - Mu Beta Psi - music; originally a men's fraternity, co-ed since 1961
- ΜΦΕ - Mu Phi Epsilon - music; originally a women's sorority, co-ed since 1977
- ΦΜΑ - Phi Mu Alpha - music; originally a men's music social fraternity since 1898, was temporarily co-ed from 1976 to 1983, but has been all-male ever since; reverted to a social fraternity in 1985 to align with its original founding
- ΦBr - Phi Boota roota - percussion; co-ed founded in 1976
- ΠΝΕ - Pi Nu Epsilon - music; co-ed music fraternity founded 1927
- ΣΑΙ - Sigma Alpha Iota - music; women's music fraternity since 1903, accepts honorary male members
- ΤΒΣ - Tau Beta Sigma - band; originally a women's sorority, co-ed since 1977
- ΓΞΦ - Gamma Xi Phi - literature, visual, and performing arts
- ΔΧΞ - Delta Chi Xi - dance; co-ed fraternity
- ΦΒ - Phi Beta - creative and performing arts
Pharmaceutical and pharmacological
- ΑΖΩ - Alpha Zeta Omega - pharmacy; originally a men's fraternity, co-ed since the early 1970s
- ΒΦΣ - Beta Phi Sigma - pharmacy
- ΚΕ - Kappa Epsilon - originally a women's fraternity, now co-ed
- ΚΨ - Kappa Psi - pharmacy; co-ed since the mid-1970s
- ΛΚΣ - Lambda Kappa Sigma - pharmacy; originally a women's fraternity, co-ed since 1988
- ΦΔΧ - Phi Delta Chi - pharmacy
- ΡΠΦ - Rho Pi Phi - pharmacy
- ΑΧΣ - Alpha Chi Sigma - chemistry; co-ed
- ΑΗΡ - Alpha Eta Rho - aviation
- ΒΨΩ - Beta Psi Omega - biology
- ΔΚΑ - Delta Kappa Alpha - cinema
- ΔΚΦ - Delta Kappa Phi - textiles
- ΓΕΤ - Gamma Epsilon Tau - printing and digital media
- ΚΔΠ - Kappa Delta Pi - education
- ΚΠ - Kappa Pi - international honorary art fraternity
- ΚΘΠ - Kappa Theta Pi - information technology professional fraternity, founded in 2012 at the University of Michigan 
- ΛΑΕ - American Criminal Justice Association–Lambda Alpha Epsilon
- ΟΔΕ - Omicron Delta Epsilon - economics
- ΦΑΤ - Phi Alpha Tau - communicative arts
- ΦΔΚ - Phi Delta Kappa - education sorority
- ΦΣΠ - Phi Sigma Pi - national honor fraternity
- ΠΜΕ - Pi Mu Epsilon - mathematics 
- ΖΦΗ - Zeta Phi Eta - communication arts and sciences
- ΖΘΩ - Zeta Theta Omega - zoology
- Title IX Archived 2007-04-03 at the Wayback Machine, United States Department of Justice
- ""Archived copy" (PDF). Archived from the original (PDF) on 2007-09-30. Retrieved 2007-07-26.CS1 maint: archived copy as title (link) Code of Federal Regulations, PART 106: NONDISCRIMINATION ON THE BASIS OF SEX IN EDUCATION PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE
- Phi Mu Alpha Sinfonia - Sinfonia's Classification
- "Sigma Alpha Iota". Sigma Alpha Iota. Archived from the original on 2010-11-30. Retrieved 2010-12-09.
- "Phi Mu Alpha". Phi Mu Alpha. Archived from the original on 2014-03-06.
- "All Comers Resolution" (PDF). Archived from the original (PDF) on March 4, 2016.
- Sigma Psi Mu
- ΑΣΚ – WiTS
- Beta Sigma Kappa http://betasigmakappa.net/. Missing or empty
- Xi Psi Phi website, accessed 21 May 2014
- Beta Psi Omega
- http://www.wix.com/uscdka/delta-kappa-alpha/[permanent dead link]
- "Archived copy". Archived from the original on 2008-04-20. Retrieved 2008-09-09.CS1 maint: archived copy as title (link)
- "Pi Mu Epsilon". Retrieved 2015-05-06.
- Zeta Theta Omega