Jean-Gabriel De Tarde or Gabriel Tarde in short (March 12, 1843 in Sarlat, France – May 13, 1904 in Paris) French sociologist, criminologist and social psychologist who conceived sociology as based on small psychological interactions among individuals (much as if it were chemistry), the fundamental forces being imitation and innovation.

Among the concepts that Tarde initiated were the group mind (taken up and developed by Gustave Le Bon, and sometimes advanced to explain so-called herd behaviour or crowd psychology), and economic psychology, where he anticipated a number of modern developments. However, Émile Durkheim's sociology overshadowed Tarde's insights, and it wasn't until U.S. scholars, such as the Chicago school, took up his theories that they became famous.

Everett Rogers furthered Tarde's "laws of imitation" in the 1962 book Diffusion of innovations.

From the late 1990s and continuing today, Tarde's work has been experiencing a renaissance. Spurred by the re-release of his essay Monadologie et Sociologie by Institut Synthelabo under the guidance of Gilles Deleuze's student Eric Alliez, Tarde's work is being re-discovered as a harbinger of postmodern French theory, particularly as influenced by the social philosophers Gilles Deleuze and Félix Guattari.

For example, it has recently been revealed that in Difference and Repetition, Deleuze's milestone book which effected his transition to a more socially-aware brand of philosophy and his writing partnership with Guattari, Deleuze in fact re-centered his philosophical orientation around Tarde's thesis that repetition serves difference rather than vice versa Also on the heels of the re-release of Tarde's works has come an important development in which French sociologist Bruno Latour has referred to Tarde as a possible predecessor to Actor-Network Theory in part because of Tarde's criticisms of Durkheim's conceptions of the Social.

A book on the Social after Gabriel Tarde, Debates and Assessments, is planned for release by Routledge in 2009, and is likely to provide the first set of mature critiques of the recent renaissance of Tarde as well as to suggest models for scholars to use Tarde's thought in their scholarship. This book is expected to include contributions that philosophically reflect the Latourian (including a contribution from Latour himself) as well as Deleuzian approaches to Tarde, and to also highlight a number of new ways Tarde is being adapated in terms of methods in contemporary sociology, particularly in the area of ethnography, and the study of online communities.

Tarde's interest in criminology arose while he was working as a magistrate in public service. Tarde was interested in the psychological basis of criminal behavior. He was critical of the concept of the atavistic criminal as developed by Cesare Lombroso. Tarde's criminological studies served as the underpinning of his later sociology .

Interestingly Tarde also produced one science-fiction novel entitled Underground Man. This novel tells the tale of a post-apocalyptic earth covered by ice where the surviving humans have gone to live underground. The novel develops on the new culture which is created by the humans where music and art are the dominating aspects of lives.