The Constitution Act, 1867 is one of the world’s oldest national constitutions in existence. This chapter explores the possibility that the longevity of Canada’s written constitution reflects design decisions made by its architects in the 1860s. It argues, more specifically, that the Canadian Constitution is characterized by “constitutional ambivalence”. It shows how this ambivalence became lodged in the design of three pillars of the constitutional order—federalism, democracy, and minority rights—and it explains how this ambivalence provided flexibility to adapt to environmental changes. It also shows how, when constitutional ambivalence was not present, for example with respect to the locus of sovereignty and Aboriginal rights, the effect was predictably de-stabilizing.