This work describes the results of the "Programa de Desarrollo Social y Afectivo" [Social and Affective Development Program] (Trianes & Munoz, 1994; Trianes, 1996), under way during four years at a public school in a disadvantaged area Malaga, earmarked for special educational resources. The intervention is meant to improve classroom and school atmosphere as an avenue to preventing school violence. We describe the intervention approach used, as well as program materials and results obtained in relation to the context variables (classroom atmosphere). The discussion presents the opportunity of improving interpersonal relationships and social atmosphere at the school as the central axis of preventive intervention against school violence. (Contains 2 tables and 3 figures.)