Constitutionalization encompasses a variety of ways in which constitutional rules emerge and change. Chapter 3 addresses the emergence and development of constitutional rules in the national context. It begins with a conceptual discussion of constitutionalization, defined as any process that brings about and changes constitutional rules. Spanning a spectrum between two ideal–type revolutionary and evolutionary pathways, constitutional processes vary with regard to frequency, intensity, output, and means of change, as well as the underlying political intentionality and contestation. The variability of constitutionalization is demonstrated empirically through a systematic analysis of national constitution–making in the United States, Sweden, and Britain in terms of the five constitutional elements identified in Chapter 2, emphasizing their similarities and differences. While this analysis will not be entirely novel to the comparative constitutional law and politics readership, it is an important building block for conceptualizing constitutionalization in the international setting.