Gabriel Tarde ranks as one of the most outstanding sociologists of nineteenth-century France, though not as well known by English readers as his peers Comte and Durkheim. This book makes available Tarde's most important work and demonstrates his continuing relevance to a new generation of students and thinkers. Tarde's landmark research and empirical analysis drew upon collective behavior, mass communications, and civic opinion as elements to be explained within the context of broader social patterns. Unlike the mass society theorists that followed in his wake, Tarde integrated his discussions of societal change at the macrosocietal and individual levels, anticipating later twentieth-century thinkers who fused the studies of mass communications and public opinion research. Terry N. Clark's introduction, considered the premier guide to Tarde's opus, accompanies this important work, reprinted here for the first time in forty years.