As can be seen from the list of faculty, the faculty are divided into categories. There are 2 primary categories: Primary Faculty are eligible to serve as dissertation advisors, as well as committee members. Primary faculty are expected to participate, according to their expertise and as appropriate, in the teaching and research training missions of the Curriculum. Primary faculty status requires a full time, tenure-track appointment in the University, eligibility to be a member of the Graduate School, and an actively funded research program. Associate Faculty are eligible to serve on dissertation committees, but not as sole thesis advisors. Such faculty may participate in teaching and serve on committees of the Curriculum. In addition, some faculty are designated as Affiliate Faculty. Affiliates participate in intellectual and other Curriculum functions, but are not available available to serve as dissertation advisors. Finally, there are Retired and Emeritus Faculty, reflecting the long history of the program. Faculty in these positions previously were primary or associate faculty.