Abstract: How is constitution-making possible, when people disagree on so many questions about what is good and what is right? The answer lies in the existence of incompletely theorized agreements–agreements on abstract formulations (freedom of speech, equality under the law) and on particular practices, amidst disagreement about the largest issues in social life. Such agreements help make constitutions and constitutional law possible, even within nations whose citizens cannot concur on the most fundamental matters. Incompletely theorized agreements thus help illuminate an enduring constitutional puzzle: how members of diverse societies can work together on terms of mutual respect amidst intense disagreements about both the right and the good.