From the Dean of the Faculty on Advisory Councils:

Consisting of persons such as faculty members at other institutions, experts and major figures in the field, alumni/ae of the University, or friends of the department, the Councils meet regularly in Princeton, typically every two years, for the purpose of advising the departments or of being of use to them in other ways. The Councils can be effective instruments for sampling the opinions of students or junior faculty members, for conveying opinions and concerns to the central administration, for serving as conduits in communicating with friends and alumni/ae, or for developing resources and generating support for the departments and their various activities. They are viewed as being under the authority and for the use of the departments and for the purposes of aiding them in whatever ways individual departments find most appropriate and helpful, especially in the areas of development and fundraising.