The IEA Civic Education Study in Portugal involved the observation of national representative samples of students from grades 8, 9 and 11. Grades 8 and 9 are the terminal years of basic (compulsory) education, and grade 11 is the mid-year of secondary education. Results on civic knowledge reveal a particular scenario that will be explored in this paper: 8 grade students score clearly below the international mean, but both 9 and 11 grade students score above the international mean. The impact of four relevant variables in the literature on political development - education, family cultural background, political interest and experiences, and interpersonal trust - will be analyzed and discussed.