Utilizing secondary data from large-scale assessment studies may help researchers and educators to identify factors to promote student’s willingness to act pro-environmentally, focusing on student and school factors. The present chapter describes the International Civic and Citizenship Education Study (ICCS) 2016, summarizing its main purpose and design, and describes the variables selected from ICCS to implement the three empirical studies included in the following chapters. The variables generated to be included in the used models are described. An ordinal logit model to model students’ willingness to act pro-environmentally in their adult life is used. A set of covariates distinguishing inequality factors between students, individual differences between students, and different school factors understood as different examples of opportunities to learn relevant for the study of environmental sustainability are included. Finally, how the data is prepared before fitting the models, the fitted model, how results are presented as conditional probabilities, and how figures are built, are described.