Purpose: Standardised questionnaires are used to measure the outcomes of citizenship education. These outcomes are often compared across groups to document different outcomes, for example, between boys and girls. A prerequisite for cross-group comparisons is an assessment of measurement invariance. Methodology: This study used data from 6035 students from 87 Dutch primary schools to examine the measurement invariance of the Citizenship Competences Questionnaire (Ten Dam et al., 2011). Dutch schools use this questionnaire to gain insight into students' citizenship knowledge, attitudes, and skills. Measurement invariance was assessed across sex, socioeconomic position, and migration background. Findings: Measurement invariance was sufficient in most cases, allowing for cross-group comparisons of associations between latent constructs and their indicators, and in some cases, for cross-group comparisons of the latent means. We conclude by emphasising that periodic assessment of measurement invariance in instruments measuring citizenship competences is important due to the dynamic nature of the construct.