The 20-item Illegal Aliens Scale, which was developed and validated by Ommundsen and Larsen at Oregon State University (1999), has been translated into Norwegian and Dutch. Cross-national comparisons of attitudes require equivalence of measurement instruments (Rogler, 1999). The results of a translation - back translation procedure and a split sample study by (Ommundsen et al., in print) suggest that linguistic equivalence may not be sufficient to detect other non-equivalence of meaning in cross-national research. This paper discusses a follow-up methodological study of the Dutch and Norwegian versions of this scale. This study consisted of two parts: (a) A 'cognitive' test by means of the three-step test-interviews (Hak et al., 2001) with Dutch and Norwegian subjects. (b) A comparative study of differences in political salience of the items of the scale between Norway and the Netherlands. Results show that differences in historical, political and cultural context result in different interpretations of seemingly straightforward concepts and that this affects how responses to attitude items are constructed.