This work presents the results of research whose main objective was to analyze the sources present in Geography and History textbooks used in Spain and Italy in secondary education, as well as how they were designed for use by the teaching staff of this subject. This research was carried out for the benefit of teachers and for the improvement of the teaching-learning process. The sample was configured on the basis of a rigorous analysis of textbooks belonging to relevant publishers in Spain and Italy, whose selection was made using a quantitative and descriptive research method based on the interpretative paradigm, with the help of an SPSS statistical program. As for the main results obtained, the data indicated that the tasks requested from students (based on the use or analysis of sources) are of a low cognitive level, which makes it difficult to learn critical and reflective historical thinking. Finally, it was concluded that for students to strengthen the development and acquisition of critical thinking, the use of textbooks must be integrated with other, more active resources and more participatory teaching strategies, putting both competency-based teaching and its assessment in quarantine.