Precise and rigorous international comparative research requires methodological reflections and determinations at each step of the empirical research process. This chapter analyzes the precision and rigor of international comparative higher education research by diagnosing their comparative methodology, particularly their country selection and case sampling. It evaluates 202 studies that have been published in journals of both higher education and comparative education, because international comparative higher education intellectually and institutionally intersects both interdisciplinary fields. The major empirical findings show a relative lack of explicit and elaborate justification strategies, as well as a lack of comparative methodology. But they also show that the intellectual and institutional context, represented here in the form of the journals, influences the implementation of comparative methodology. The use of comparative methodologies is more thorough in the context of comparative education, where a continuous debate about the theoretical and methodological aspects of comparative studies takes place. One of the implications of the study is that the debate regarding comparative methodologies within higher education research should be intensified.