The problem of responsibility in moral philosophy has been lively debated in the last decades, especially since the publication of Harry Frankfurt's seminal paper, 'Alternate possibilities and moral responsibility' (1969). Compatibilists - also known as 'soft' determinists - and, on the other side, incompatibilists - libertarians and 'hard' determinists - are the main contenders in this major academic controversy. The debate goes back to Antiquity. After Aristotle, compatibilists, and especially the Stoics, debated this issue with the incompatibilists, notably Epicurus (though his classification as an incompatibilist has been disputed in modern scholarship), Alexander of Aphrodisias and Plutarch.The problem debated at that time and the problem debated nowadays are fundamentally the same, even though the terms and the concepts evolved over the centuries. In Antiquity, the central notion was that of 'what is up to us', or 'what depends on us'. The present volume brings together twenty contributions devoted to examining the problem of moral responsibility as it arises in Antiquity in direct connection with the concept of what is up to us - to eph' hêmin, in Greek, or in nostra potestate and in nobis, in its Latin counterparts, aiming to promote classical scholarship, and to shed some light on the contemporary issues as well.With contributions by Marcelo D. Boeri, Mauro Bonazzi, Susanne Bobzien, Pierre Destrée, Javier Echeñique, Dorothea Frede, Michael Frede, Lloyd P. Gerson, Laura Liliana Gómez, Jean-Baptiste Gourinat, Christoph Horn, Monte Ransom Johnson, Stefano Maso, Susan Sauvé Meyer, Pierre-Marie Morel, Ricardo Salles, Carlos Steel, Daniela Patrizia Taormina, Emmanuele Vimercati, Katja Maria Vogt, Christian Wildberg and Marco Zingano.