Knowledge about ecology and environmental education (EE) constitutes a basic tool for promoting a sustainable future, and was a target area of the BIOHEAD-Citizen Project. School textbooks were considered as representative sources of evidence in terms of ecology and environmental education, and were used for comparison among the countries participating in BIOHEAD-Citizen Project. The main goal of the analysis was to highlight the implicit and explicit values conveyed both by images and text in the respective textbooks from each country. This paper presents the theoretical background that guided the process of designing and development of several grids that were then used for analyzing samples of textbooks from 19 different countries. The paper also provides brief information indicating how EE is contextualized within each participating country's curriculum. (Contains 4 tables.)