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 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 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 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.