This chapter provides an overview of a number of basic aspects of the constitution that will need to be taken into consideration by constitutional drafters regardless of the institutional choices they make. It begins by outlining the key elements usually regulated in constitutions, and how they are often an instrument of national self-expression. It goes on to discuss key elements of the frame of government, including its territorial structure (which is further elaborated in Chapter 4) and the three powers (the executive, legislative and judiciary). It concludes by providing an overview of the most common mechanisms included in OECD member countries’ constitutions for constitutional amendment and stability.