Charles Tilly (1929-2008) was the Joseph L. Buttenwieser Professor of Social Science at Columbia University. His books include "Why?" (Princeton) and "Democracy".
Lesley J. Wood is Assistant Professor of Sociology at York University. Her work on globalization and social movements has been published as book chapters and in the journals Mobilization and the Journal of World Systems Research. She is currently working on a monograph about diffusion and direct action tactics.