Academic self-concept and academic interest are crucial concepts for understanding students' academic achievement. Yet, few questionnaires currently exist that have been used and validated in more than one country. This study aimed at assessing these concepts using an academic self-concept questionnaire (Marsh, 1990) and an academic interest questionnaire (Corbiere & Mbekou, 1997) with French and Italian student samples. Confirmatory Factor Analyses enabled us to assess the structure of the two questionnaires with regard to two academic subjects--Math and First Language (French or Italian)--and to determine the theoretical directions between the concepts. Results from Confirmatory Factor Analyses of both French and Italian samples supported a theoretical model in which academic self-concept and academic interest were intercorrelated, yet maintaining their unique characteristics. On the other hand, results from Multi-Sample Confirmatory Factor Analyses (French and Italian samples) endorsed a correlational model between the two concepts. Finally, the results indicated a significant and positive correlation between academic self-concept, academic interest, and academic achievement in both academic subjects. (Contains 4 tables.)