This work presents a new critical edition of The Spartan Constitution, a treatise in state philosophy attributed to the historian Xenophon (c. 430 - c. 355 B. C.). The Greek text, reconstructed on the basis of extant manuscript sources, is prefaced by an introduction and supplemented by a critical commentary and an English translation. The introduction discusses the problem of the text's authenticity and dating and provides a comprehensive account of its sources, reception, language, style and structure as well as an analysis of the manuscript sources and the textual tradition. The commentary addresses linguistic as well as historical problems.