Thirteen primary and pre-primary schools in Extremadura (Spain) were participants in an educational research project, "Ecocentros", based on school environmental audits (eco-audits). To understand the contribution these experiences can make to achieving the objectives of environmental education, it is essential to know what is actually incorporated into the curriculum and how. Progress was made in the integration of environmental education at the classroom level. This strengthens the development of the processes of participation and the motivation of the pupils and the teaching community. (Contains 3 tables and 1 figure.)