Miss. Code Ann. § 25-11-401

There is established an optional retirement program for employees of the state institutions of higher learning included in Section 37-101-1, Mississippi Code of 1972 , who are appointed or employed after July 1, 1990. To be eligible to participate in the optional retirement program, a newly appointed employee must: (a)(i) Hold a teaching or administrative faculty position, or (ii) Hold a position as an intern or resident in training at the University Medical Center or the College of Veterinary Medicine at Mississippi State University under a teaching program at such institutions; and (b) Be eligible for membership in the Public Employees' Retirement System of Mississippi.