The essays in this book analyse the political writings of the main exponents of English republicanism: John Milton, Marchamont Nedham, James Harrington and Algernon Sidney. While republicanism had a long tradition on the European continent, in England its full expression only occurred during the republican regime established between 1649 and 1660. During the first decades of the 17th century, in the increasingly fierce confrontation between King and Parliament, the republican ideology was slowly incorporated into the English political debate, in an intricate process of appropriating different matrices of republican thought and adapting its principles to England's political and legal tradition. In this process, certain principles were maintained, others modified and some completely abandoned. The purpose of the essays published here is to understand the result of this process and the peculiarity of English republicanism, which decisively marked modern republican thought.