The degree of doctor of philosophy (Ph.D.), introduced to this country by Yale in 1861, is the highest degree offered in American education. It is conferred in recognition of two accomplishments: (1) marked ability and scholarship in a broad field of learning (such as chemistry or classics), and (2) distinguished critical or creative achievement within a special area of the general field. The special field forms the subject of the doctoral dissertation. A student must devote a minimum of three years of full-time study beyond the bachelor's degree for the Ph.D., of which at least one year must be devoted to dissertation-related research. One year of study is represented, for this purpose, by 24 credits of coursework or research. The minimum requirement for the Ph.D. degree is, therefore, 72 credits, of which at least 24 credits must be devoted to research. If any of the work is conducted on a part-time basis, the minimum time required will, of course, be longer.

Doctoral programs normally are arranged in two phases. The preliminary phase, which generally involves formal courses of study, is completed when the student passes the qualifying examination. In the second phase, the student usually pursues research courses and writes his or her dissertation. This phase concludes when the dissertation is accepted and the defense of it is approved. Between admission to the Graduate School–New Brunswick and the conferral of the Ph.D. degree, the student must (1) satisfy the course and other preliminary requirements of the particular graduate program in which the student is enrolled, (2) pass the qualifying examination, (3) present the results of the special research in an acceptable dissertation, and (4) pass a final examination related to the subject of the dissertation. The student becomes a formal candidate for the doctorate only after completing the qualifying examination.