Organizational rules explain organizational stability and change. Using national surveys and fieldwork, we examine changes in tenure and promotion rules at comprehensive colleges and universities from 1969 to 2002. We find that increased rule founding and change arise from the increasingly rationalized environment, such as the academic profession's normative standards and complex regulatory demands. Notably, institutions adopted the more legitimate rules of research universities and liberal arts colleges. (Contains 2 tables, 4 figures and 4 notes.)