Wim Savenije is researcher and lecturer with the department of Social and Political Anthropology at the Facultad Latinoamericana de Ciencias Sociales (FLACSO) in Argentina. His areas of interest are violent youth groups and the transnational street gangs or ‘maras’ in Central America, the relationship between the security forces and communities with high levels of insecurity and the dynamic relation between marginalization. Additionally social exclusion and the incidence of violence and the possibility of employing social prevention strategies to diminish violence and delinquency at neighbourhood level. The topics of his PhD are the dynamics of social and auto exclusion fomented by the Mara Salvatrucha (MS-13) and the Eighteen Street Gang (Barrio 18), and student gangs in Central America. He has extensive field experience in the various countries of the region. His current research focuses on 1. the continuing development of the ‘maras’ and the relationship with the often makeshift security policies in the Central American region; 2. the efforts of security forces (police and military) to alleviate the insecurity caused by the street gangs in urban neighbourhoods; 3. how growing up and living in neighbourhoods with high level of insecurity affects the lives of ordinary (no-gang) youths; and 4. how initiatives focussing on the social prevention of violence can influence the lives of youth at risk.