Higher education is the education level under the most pressure to be internationally liberalized. Currently, the main global instrument to achieve this liberalization goal is the General Agreement on Trade in Services (GATS) of the World Trade Organization. In this paper, the process of trade liberalization of higher education in the GATS framework is examined. The analysis is divided into two main parts. First, the state of the current situation of higher education liberalization and that of other education sectors are reviewed and compared. Second, the factors that influence the undertaking of liberalization commitments on education, specifically higher education, are analyzed. To make these comparative analyses, EduGATS, a novel index to measure the degree of liberalization of educational services, is introduced. (Contains 5 tables, 8 figures and 4 notes.)