President Greiner joined the UB law faculty in 1967 and shortly thereafter became chairman of the Legal Studies Programs. By 1984, he was named UB's first University Provost. He served as interim president from March 1991 until his appointment as president by the Chancellor and Board of Trustees on September 25, 1991. Greiner's accomplishments as president included creating numerous trans-disciplinary research centers and institutes; reaffirming the University's commitment to public service; streamlining student services and record enrollments; increasing exchange and study abroad programs; conducting a record-breaking capital campaign; constructing a series of student residential centers and other major construction projects; creating of Task Forces on Women and on Racial and Ethnic Diversity; and moving the UB football team to Division 1-A.