The main objective of this paper was to examine the interests in acquiring knowledge about certain European values and the cultural substance of national, ethnic and regional groups of Istrian secondary-school youth in the Republic of Croatia. The existence of interest was examined with regard to sex, school success, the father's degree of education and nationality of the examinees. 763 students of Croatian and Italian secondary schools from Istria and Rijeka participated in the research. The results obtained indicated that secondary-school girls were more interested in knowing certain elements about the cultures of national and ethnic groups than the boys. This interest was most expressed in examinees from the Istrian and Kvarnerian area who had the strongest wish to become acquainted with the cultural customs of all regional groups in Croatia. Students with higher grades showed greater interest in "knowing about the others", while those whose fathers were more educated expressed greater interest in European values. Members of the Italian and Serbian nationalities expressed greater interest in the culture of the host nationality, than the Croats showed for the cultures of other national and ethnic groups. Members of different nationalities (Croats, Italians, Serbs) demonstrate a significantly diverse general interest in the dialects and customs of regional groups in Croatia. Also, there is a statistically significant difference in the interest manifested for knowledge about the Catholic, Muslim and Orthodox religion, with regard to the nationality of the examinee. Examinees of Croatian, Muslim and Serb nationalities have demonstrated statistically significant differring interests for understanding the customs of Muslim, Orthodox and Catholic religions. The greatest difference of interest in acquiring knowledge about these religions was found between Muslims and Croats.