Part-time and full-time non-tenure track faculty currently represent almost half of all faculty in U.S. higher education, yet little is known about their earnings relative to tradition tenure-track faculty. This paper finds that full-time non-tenure track faculty earn approximately 26 percent less per hour from their academic institution and 18 percent less in total earnings from all sources per hour than comparable tenure track assistant professors. Part-time non-tenure track faculty earn 64 percent less per hour from their institution, but only 1 percent less in total earnings per hour than tenure track assistant professors.