The project Biology, health and environmental education for better citizenship, (BIO-HEAD CITIZEN) aimed to improve understanding of how different aspects of citizenship, including affective and social dimensions, are promoted through Biology, Health and Environmental Education. It developed a critical analysis of syllabus and schoolbooks as well as of teachers’ and teachers-to-be’ conceptions. The project was largely comparative across the 20 countries involved in the project, through two approaches: Critical analysis of the selected syllabus topics and the analysis of teachers’ and teachers-to-be’ conceptions from questionnaires and interviews regarding implicit values related to each topic. Such comparative work was complemented by some case studies.