What is constitutional review? Although the question itself does not connote any institutional contexts, traditional literature has typically defined it as “the power/practice of courts to evaluate and determine the conformity of political acts with the constitution.” As a result, the concept and practice of constitutional review has been largely equated to one led by courts. Unfortunately, such synonymization overshadows the empirical reality of non-judicial bodies serving central reviewing roles in major democracies such as the Netherlands, Finland, and Japan. By viewing constitutional review as a functional concept, from the institutional design perspective, this Article questions that scholarly tendency and proposes a working definition of constitutional review as an institution-independent concept. This approach in turn encompasses institutional diversity inherently embedded into the practice of constitutional review. Anchored by such a vision, the Article attempts to demonstrate key implications and values for conceptualizing constitutional review independently from institutions and actors. Referring to concrete examples from different countries, it categorizes and juxtaposes existing constitutional review models led by various institutions on the same spectrum (treating court-led review models as only one such category). Using a few countries as an example, the Article also preliminarily discusses how and where to institutionalize the practice of constitutional review so as to design an optimal review mechanism for countries. In conclusion, the Article calls for a new research direction to establish the general literature on constitutional review that reflects the institution-independent concept.