Gustav Bergmann (1906-1987) was, arguably, the greatest ontologist of the twentieth century in pursuing the fundamental questions of first philosophy as deeply as any philosopher of any time. In 2006 and 2007, international conferences devoted solely to Bergmann's work were held at the University of Iowa in the USA, Université de Provence in France, and Università degli Studi Roma Tre in Italy. The papers in this volume were presented at the first of these conferences, in Iowa City, where Bergmann taught for nearly four decades after escaping from Europe, following the dissolution of the Vienna Circle of which he had been the youngest member. There are nine philosophical papers, reminiscences of three of his students, and a complete bibliography of his published writings.