The Class Records consist of a diverse set of materials documenting the history and activities of Princeton University classes during their time as undergraduates and as alumni. In the collection are correspondence, newsletters, publications, photographs, and memorabilia, all of which pertain to a particular Princeton University graduating class and its members.

The most common type of material in the collection is class secretary records consisting of correspondence to individual classmates. These letters regard updates to class notes, questionnaires sent to classmates regarding their information to be updated in reunion books, directories, and other publications, as well as University sponsored events such as Alumni Day, football weekend, faculty lectures, and most importantly Reunions. Heavily documented in these records are the activities of the reunions committee for many classes in planning major reunions. In addition to class secretary files, administrative correspondence is also included from various committees serving under the Alumni Association of Princeton University as well as from regional alumni associations. The most common among these are the Princeton Club of New York and the Princeton Club of Philadelphia, respectively.

Of particular note in the Class Records are 19th century proclamations, broadsides printed and posted by classes (often the freshman or sophomore class) to insult each other or declare the end of hazing periods. These posters are often humorous and feature typical 19th century typefaces and design.

In some instances donations made by individual alumni have been included in the Class Records collection. These often consist of undergraduate material relating to class day exercises, sophomore dances, junior orations, class photographs, and sometimes scrapbooks. Additionally, pieces of memorabilia such as hat bands, pins, and banners used at reunions have been included in this collection.

Though nearly all alumni classes are represented in the Class Records to some degree, the amount of material pertaining to any particular class varies greatly. By far the largest amount of material is related to classes from the late 1890s to the 1940s. Documentation for classes from the 18th century consists almost entirely of secondary materials compiled by later researchers.