Resumen: This book makes a critical examination of the Stoic theory of oikeiôsis offering a systematic reconstruction of the natural basis of morality within this philosophical school. What is striking about this theory is the fact that, despite being guided by the notion of self-preservation, the Stoics did not develop an ethics of survival or assume any other variant of the usual ethical egoism but rather developed a model of ethics replete with social content, which takes on a decidedly universal and cosmopolitan character. Through a detailed study of classical sources and in dialogue with leading contemporary scholars in the field of Stoic studies, the author accounts for the different stages of the process of modulation of natural impulses that occurs in human beings with the emergence of reason and also explains in what sense the attainment of virtue is for a Stoic equivalent to a ¿life in accordance with nature¿.