Complex sentence: He served as provost of Princeton University between 1977 and 1988, as executive vice-president of the Andrew W. Mellon Foundation from 1988 to 1991, and as president of Harvard University from 1991 to 2001.
Split into simpler sentences: He served as provost of Princeton University between 1977 and 1988. He then served as president of Harvard University from 1991 to 2001.