This chapter argues that Thucydides’ History provides for its readers an opportunity to assess the limits and opportunities of diverse political regimes, particularly democracy, oligarchy and monarchy. In doing so, he offers insights not only into the specific characteristics of the cities that employ those regimes (Athens, Sparta, Corinth, Thebes), but also into what is distinctive about those regime types, understood in categorical terms. The chapter focuses on Thucydides’ presentation of democracy in Athens and in Syracuse, arguing that Thucydides, although alert to the weaknesses of democracy, was also an admirer of the attainments and ambitions of this form of governance.