Universities elsewhere have been changing its purposes, functions, roles, and pursuits in society. This study is a case study of Mongolian higher education in which institutional changes are taking place incrementally. The purpose of this study is to explore institutional isomorphism or homogenization of a case university in Mongolia in two different periods of which one is a university under the Soviet regime in the past, and the other is under the democracy in present. The research question was how a university in Mongolia has been changing isomorphically under the different environmental pressures. The study applied a single case study proposed by Yin (2003; 2009) to explore homogenization or isomorphic changes at one prestigious higher education institution in Mongolia. Interviews, reports, and other related documents were used for the analysis. The analytical procedure applied main elements of qualitative research methods. The findings are discussed in three major themes: coercive isomorphism of a university, isomorphic changes triggered by the faculty members: bottom-up process, and mimetic isomorphism modeling after American higher education. It is concluded that the institutional changes taken place in the university was first pressured by the coercion dictated by the political social circumstances, that is, Soviet regime; second, by the faculty members triggered by the professionalization; and third, by the mimicry modeling after successful higher education institution, an American higher education system.