A co-ed fraternity is, simply put, a fraternity that is co-educational, that is to say, it accepts membership from members of both sexes.
The majority of co-ed fraternities are either service or professional fraternities. Within the United States, all honour societies and service and professional organizations, whether they identify themselves as a member of "the Greek System" or not, are prohibited from discrimination upon the basis of sex. Social fraternities and sororities, which are the type that most people think of when they hear the word, are granted an exclusion from the act barring such discrimination.
Many of these organizations function differently from your typical fraternity or sorority. The entrance requirements may be different, such as Alpha Kappa Psi, who only accepts students majoring or minoring in business, with at least a 2.5 GPA, or Kappa Eta Kappa, whose membership is limited to those majoring in Computer or Electrical Engineering, or Computer Science.
The primary difference is in the focus of the fraternity's activities. Professional fraternities are primarily about developing skills to be used later on in your career, networking, and promotion of the profession. Service fraternities, naturally, are all about volunteering, either focusing on a particular cause or allowing individual chapters to determine their activities. One major difference between these and social fraternities is that chapters of social fraternities are much more likely to own a fraternity house.
While some of these organizations may be primarily male or female (With the primarily female ones generally referring to themselves as sororities), the vast majority do accept both males and females.
There are also a few social co-ed fraternities. They are, however, not nearly as prevalent as non-coed fraternities. A quick look at Wikipedia lists a mere 9 national co-educational fraternities, at least one of which appears to actually be a professional fraternity. It also appears that co-ed social fraternities are also unlikely to own chapter houses. The majority of co-ed fraternities out there are local organizations, limited to a single chapter.
This is at the same time understandable, and disappointing. Living with a large group of all guys or all girls can be tough enough. Mix the two, and you may well be asking for trouble. As well, being smaller, and relatively newer, these organizations may have simply not have had time to build up the resources necessary.
But, it is disappointing. It has been my experience that the fraternity house is a key element of the "Greek" experience. A place to live amongst your peers, a base of operations, and a refuge from the stress of university life. Being a part of the Greek system is more a lifestyle than anything else, and it is hard to accomplish without a chapter house.
I am going to be rather frank here. In my not so humble opinion, a co-ed fraternity without a chapter house is little more than a student club with a funny sounding name.
Your mileage may vary.
Leah Gliniewicz, "The Greek Alternative: Co-ed Fraternities," Young Money. 19 April 2005. <www.youngmoney.com/lifestyles/campus_life/050420> (19 Dec 08.)
Wikipedia. "Professional fraternities," Wikipedia, the free encyclopedia. 17 Nov 08.
<en.wikipedia.org/wiki/Professional_fraternities> (19 Dec 08.)
Wikipedia. "Service fraternities and sororities," Wikipedia, the free encyclopedia. 17 Dec 08.
<en.wikipedia.org/wiki/Service_fraternities_and_sororities> (19 Dec 08.)
Wikipedia. "List of social fraternities and sororities," Wikipedia, the free encyclopedia. 17 Dec 08.
<en.wikipedia.org/wiki/List_of_social_fraternities_and_sororities#Coeducational_Fraternities> (19 Dec 08.)