Knowledge Spillovers and the Geography of Innovation Prepared for the Handbook of Urban and Regional Economics, Volume 4 Revised May 9, 2003 David B. Audretsch* & Maryann P. Feldman** *Indiana University and Centre for Economic Policy (CEPR) **University of Toronto Acknowledgements: We acknowledge the comments of Vernon Henderson, Jacque Thisse, Will Strange and the participants at the CEPR Meetings in December 2002. We are also grateful to the comments and suggestions made by Luigi Guiso. Feldman acknowledges financial support of the Connaught Fund at the University of Toronto. Comments are welcome and appreciated.