When items eliciting attitudes or believes towards immigrants are used in cross-cultural research to compare country levels in xenophobia, equivalence of measurement across countries is a necessary prerequisite. Equivalence requires that respondents in all countries have at least “comparable” groups of immigrants in mind, though this might include different groups in terms of ethnicity, qualification or legal status.We use specific probes implemented in online access panels in seven countries/regions to elucidate which groups of immigrants respondents think of when answering immigration items from the International Social Survey Program 2003 module on “National Identity”. We find that argumentation patterns of respondents are by and large similar across countries, though specific groups mentioned in different countries are not identical. The panel results are used to shed light on what might have happened in the actual ISSP survey.