This chapter introduces the U.S. Constitution by exploring its purposes, functions, and significance as a written document, contrasting it with Britain’s unwritten constitutional system. It argues that a written constitution limits governmental power, including legislative authority, unlike the British system of parliamentary supremacy. The chapter traces the American shift in the 1760s toward viewing constitutions as superior laws fixed by the people’s consent and enforceable against the legislature. It outlines the settlement functions of constitutions – establishing government structures, ensuring stability, and channeling disputes – emphasizing how written constitutions enhance these functions. The chapter further examines the ends of free government, balancing liberty and order through democratic self-governance and the protection of natural rights, as articulated in the Declaration of Independence and the Constitution’s preamble. It introduces the Constitution’s structural features – separation of powers, federalism, checks and balances – while addressing critiques of its alleged undemocratic nature and introducing the Founders’ intent to create republican remedies for the diseases most incident to republican government.