This book presents some of Zoltán J. Ács’ most important contributions since the turn of the the new millennium, with a particular intellectual focus on the knowledge spillover theory of entrepreneurship. This approach was shaped by three major events: the rapid globalization that occurred in the first decade of the 21st century; research on the role institutions have played in economic development during the past few decades; and the spread of entrepreneurial activity around the world following the collapse of communism at the end of the 20th century. This entrepreneurial activity has given rise to many questions of theory, measurement and policy.