This Liber Amicorum was launched on the occasion of Professor William E. Kovacic's retirement from the U.S. Federal Trade Commission where he served as Commissioner from January 2006 to October 2011, as the Chairman from March 2008 to March 2009, and as a General Counsel from 2001 through 2004. This Volume I pays tribute to William Kovacic's work as a professor, public official and "international entrepreneur," which has tremendously contributed to the development of the U.S. and international antitrust law. This first volume includes 31 contributions by his colleagues and friends mainly from the United States, and it is divided into two sections. Part I, entitled "An Antitrust Career," contains 10 articles that offer an original as well as enthralling picture of Kovacic as professor, lawyer, unconventional thinker and innovator of antitrust law. Part II, entitled "New Frontiers of Antitrust," consists of 21 articles covering different aspects of competition law, ranging from cartels to mergers analysis, private rights of action, antitrust settlements, etc. The overall result is a collective work that offers the opportunity to look over the antitrust world not only as a "cold" field of law, but also as a lively discipline to whose growth Professor Kovacic has contributed so much.