During his time at Texas Tech University, Nellis has focused on campus-wide innovation and entrepreneurship, enhancing diversity on campus and developing community partnerships. He has hired additional staff and faculty as the university's enrollment has grown to almost 36,000. Likewise, Texas Tech has added research professorships and enhanced efforts toward inter-disciplinary research. He also was instrumental in the university's recent reaccreditation from SACSCOC (Southern Association of Colleges and Schools Commission on Colleges).