Casteen served as the eleventh president of the University of Connecticut from August 1985 through October 1990. In 1987, the university became the first public university in New England to ascend to the top-tier ranking of Doctoral Universities - Very High Research Activity (R1) of the Carnegie Classification of Institutions of Higher Education. Enrollment rose from 23,878 students in 1985 to 26,478 in 1990, while the university's endowment rose from $2 million to $23 million. However, UConn continued to struggle with shrinking state support and deteriorating campus infrastructure.