Cicero's On the Commonwealth and On the Laws were his first and most substantial attempt to adapt Greek theories of political life to the circumstances of the Roman Republic. They represent Cicero's vision of an ideal society, and remain his most important works of political philosophy. On the Commonwealth survives only in part, and On the Laws was never completed. The present volume offers a scholarly reconstruction of the fragments of On the Commonwealth and a masterly translation of both dialogues, newly prepared by James E. G. Zetzel, Professor of Classics at Columbia University. The texts are supported by a concise introduction, notes, synopsis, biographical notes and bibliography, all designed to assist students in politics, philosophy, ancient history, law and classics.