[1][2] Membership in the fraternity is open to honorable men[3] studying at one of Aachen's universities and is based exclusively on personality, good moral standing, and strength of character.

[1] The fraternity encourages freshly admitted (pledging "fox") members with diverse ethnic, national, religious and political backgrounds to prove themselves as valuable Corps brothers, purely on the basis of personal character and merit, before becoming eligible to be fully incorporated (Rezeption).

[4][6] The fraternity has about 300 members of all ages (including alumni) coming from or currently residing in Europe, Asia, the Americas and Africa.

[5][6][8] Marko-Guestphalia's members identify themselves wearing the traditional couleur, colored stripes, as well as caps and/or other specific garments at official occasions.

With the goal to achieve members who are prepared to become active leaders in society, every Corps brother is expected to hold a leadership position at least once for a term ("Semester") while a student.

[4] Similarly, every member must finish his higher educational degree with good academic standing in order to advance to the status of Alter Herr (alumnus).