To illuminate the process through which certain legal ideas become reality – that is, become treaties or laws – it is necessary to examine how these ideas fit with the political needs of a particular moment and with existing configurations of power, interests, and resources. This chapter focuses on political history, or scholarship that aims to understand the political context in which a particular treaty or law was drafted. The first half of the chapter discusses the promise and methodological challenges associated with researching the political history of legal texts. Then the chapter turns to a case study on the drafting of the ICSID Convention. The key innovations that allowed ICSID to succeed were political: the World Bank put its reputation behind the idea and framed the idea of investor-state arbitration in a way that could command wide support, and then designed a novel non-deliberative drafting procedure.