From doc: http://www.med.nyu.edu/faa/docs/revision.doc#_Toc520006595

Non-Tenure Track, Part-Time, Faculty Titles

    Appointment to these tracks should be considered for anyone qualified as specified below who desires to be affiliated with the School and who wishes to pursue any of a variety of careers that include service to the School.

Clinical Track
Faculty members in this track will fulfill a variety of teaching, clinical and service responsibilities in the institution according to the needs of the departments and divisions. They will be awarded the titles of Clinical Assistant Professor, Clinical Associate Professor or Clinical Professor of the specific discipline. These faculty members will be expected to demonstrate excellence in patient care and teaching, and, when appropriate, to contribute to the service activities of the School of Medicine. Faculty in this track shall be reviewed every three years by the Departmental Appointments and Promotions Committee to determine whether a recommendation for promotion within this track should be sent to the Dean.

Clinical Assistant Professor
The rank of Clinical Assistant Professor of (specific discipline) may be granted to those who have earned a terminal degree (or its equivalent) appropriate to their field, and have given evidence of character and dedication to patient care. They should also be qualified to teach in the School of Medicine and its clinical programs. Appointment as Clinical Assistant Professor of (specific discipline) carries with it the possibility, but no presumption, of reappointment or to further appointment or promotion to any higher rank. There is no time limit upon appointments in this track. Appointments will be of one year's duration and there will be no limit on the number of reappointments.

Clinical Associate Professor
The rank of Clinical Associate Professor of (specific discipline) should be granted to those members of the full-time faculty who have served as Assistant Professors at NYU or elsewhere, who demonstrate clinical excellence in their specialty and fulfill important service or teaching responsibilities at the School and its affiliated hospitals. As members of the academic community they shall be expected to contribute to scholarly activities and shall participate in medical, graduate or post-graduate teaching activities. These appointments must be approved initially by the Departmental Appointments and Promotions Committee, proposed by the Chair of the department to the Dean, recommended by the School Committee on Appointments and Promotions and endorsed by the Dean. Appointments will be of one year's duration and there will be no limit on the number of reappointments.