Keywords: Italian citizenship, foreigner, official statistics, classification criteria.
School administrations officially define the foreign pupil as «a student with non-Italian citizenship». This formal classificatory criterion, however, has not been adopted in empirical sociological research: schools usually prefer not to supply such information due to privacy legislation; citizenship is frequently an unfamiliar concept for students. Social researchers have thus elaborated alternative expedients in order to distinguish foreign students from Italians. Information about the place of birth both of students and their two reference adults is the most common expedient adopted. The aim of this paper is to examine the discrepancy between the two criteria in order to investigate: if, and to what extent, foreign students' classification criteria used by sociological surveys distort information collected by official statistics; in which direction does this bias operate; if it is possible to identify a classificatory criterion that better accommodates sociological research goals. This analysis uses data gathered during the 2009/10 school year by means of a questionnaire distributed to 1,080 students (including 510 non-Italians) enrolled in upper secondary schools of Bologna.