This article discusses educational inequalities within the territorial context of Spain, and more particularly in the autonomous community of Catalonia. The analysis, which takes a comparative international approach, looks at the question from two points of view. First, from the angle of students, an analysis is made of the impact produced by variables associated with their social, economic, and cultural status according to their educational differentiation. Second, from the angle of schools, the article analyzes the role these play in either offsetting or emphasizing these inequalities. The study was developed on the basis of a statistical analysis of the data contained in the PISA 2003 database, which covered a total of 276,165 students of 10,104 schools in 41 different countries (30 OECD member countries and 11 non-member countries). In the case of Spain, the sample consists of 10,791 students and 383 schools, and for the autonomous community of Catalonia 1,516 students and 50 schools. (Contains 3 tables, 11 figures, and 8 endnotes.)