International studies tend to use student, teacher or school questionnaires for the collection of contextual data on student or teacher characteristics, background, activities and the school's learning environment. Furthermore, student measures of values, attitudes and behavioural intentions are also frequently viewed as important learning outcomes, in particular in the context of studies of civic and citizenship education. Data obtained from these instruments become frequently important predictors of student performance or are treated as learning outcome variables of interest. Therefore, the scaling of questionnaire items to obtain measures of students', teachers' and principals' perceptions and attitudes should ideally be subject of a thorough cross-country validation of the underlying constructs. However, whereas international studies use to spend considerable efforts on ensuring measurement equivalence for international test instruments, the issue of equivalency of questionnaire data does not always receive quite the same attention. Using a set of student questionnaire items as an example, this paper describes how measurement equivalence was reviewed in the field trial analysis for the IEA International Civic and Citizenship Education Study (ICCS) using different methodological approaches including factor analysis and item response modelling.