Rosario Ortega Ruiz Psiclogía is professor of the University of Córdoba. His research has focused on interpersonal relations as a field of learning and development. He has studied children's play and the social construction of knowledge, a subject on which he has published a considerable number of articles and several books, including: Play, Activity and Thought: Reflections on Piaget's and Vygotsky's Theories. In DE Litle (Ed.): Play and Educational Theory and Practice. Praeger. Westport. Connecticut. USA. In recent years, the study has focused on school and youth violence issue which has published the following works among others: School Violence. Prevention Strategies. Barcelona (2003), Grão