Kroll began his ministry as the pastor of First Baptist Church in
Middleboro, Massachusetts (1968–1970). He then taught at Practical Bible Training School (now
Davis College) 1971–1973. From 1975 to 1980, he chaired the Division of Religion at
Liberty University in
Lynchburg, Virginia. On January 17, 1981, Kroll was inaugurated as president of Practical Bible Training School, also teaching Bible and preaching while serving as president. During Kroll's presidency, the school obtained accreditation from the
Transnational Association of Christian Colleges and Schools (TRACS) and the American Association of Bible Colleges (AABC, now the
Association for Biblical Higher Education). He also developed the administration, curriculum, and much of the school's structure as it exists today, now as
Davis College. Kroll resigned on April 27, 1990, to become President and Senior Bible Teacher of the
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