After describing the historical and social context and the development of cooperation and mutual help among students throughout the history of education in El Salvador, I have summed up the results of a recent survey on perceptions and experiences of CL among teachers in different schools. In the most extensive part of this dissertation I have described a comunidad in one of the marginalized municipalities of San Salvador, the situation and perspective of its inhabitants, its relationship to the outside and to professionals who to different degrees seem to be insiders and outsiders at the same time.