<p>Terms such as “authoritarian constitutionalism” or “populist constitutionalism” attest to the enduring appeal of the concept of constitutionalism, even when its dignity is strained by the addition of such adjectives. This insouciance may stem from a general disinterest in the question of what constitutionalism actually <i>is</i>. This review article engages with classic authors such as McIlwain and Loewenstein, and even more closely with the lesser-known Hermann Heller, to investigate the concept of constitutionalism and to assess whether its enduring appeal to scholars and politicians involves more demanding implications than often assumed. The article begins with a distinction between a semantic and a nonsemantic perspective, as it is not clear to which of the two perspectives McIlwain’s and Loewenstein’s assumption that constitutionalism is a very ancient concept belongs. After taking a closer look at the centuries-long development of the constitution in the nonsemantic field, so as not to get stuck in a mere dispute over terms, the article turns to Heller’s innovative approach. He invites us to consider a <i>strict</i> definition of constitutionalism, as he emphasizes the need to distinguish between “factual normality” and “normativized normality.” As a result of reviewing these authors, reasons are identified for not deriding non-Western forms of organizing and even limiting state power through means other than the constitution. It is suggested that for a <i>strict</i> definition of constitutionalism it is important to separate it from normative and moral expectations, as well as from liberalism and democracy.</p>