Peter Marsden, the Edith and Benjamin Geisinger Professor of Sociology and a Harvard College Professor, has been appointed the new dean of social science by Faculty of Arts and Sciences (FAS) Dean Michael D. Smith. He begins his new role on Jan.1, 2011.Marsden came to Harvard in 1987, and twice served as chair of the Sociology Department and of the Program and Admissions Committee for the Ph.D. Program in Organizational Behavior. His research interests center on social organization, especially formal organizations and social networks. He has ongoing research and teaching interests in social science methodology, especially survey research techniques and methods for the collection and analysis of social network data.Marsden replaces Stephen Kosslyn, John Lindsley Professor of Psychology in Memory of William James, who was recently named director of the Center for Advanced Study in the Behavioral Sciences at Stanford University. Kosslyn, who first arrived at Harvard in 1977, has served as dean of social science since July 2008. Smith celebrated Kosslyn’s service to Harvard at a University Hall reception on Wednesday (Nov. 17).Stephen Kosslyn, who first arrived at Harvard in 1977, has served as dean of social science since July 2008. He was honored for his service to the University at a Nov. 17 reception.