The European Psychiatric Services: Inputs Linked to Outcomes and Needs (EPSILON) study was a EU BIOMED-2-funded comparative, cross-national, cross-sectional study aimed (1) to produce standardized versions of five key research instruments in five languages, and (2) to compare the characteristics, needs, and life qualities of people with schizophrenia and their caregivers in these five countries. One of the key instruments was the Involvement Evaluation Questionnaire (IEQ), an instrument to assess caregiving consequences. In this article, the intercultural validity of the IEQ is described. It was concluded that the IEQ covers the same caregiving domains in all five countries: interpersonal tension, worrying, urging, and supervision. Differences in score levels between countries were found. When adjusted for variables known to correlate with IEQ scores (patient, caregiver, and relationship), these differences still persisted. It could not be determined how far the remaining variation could be explained by site-level characteristics, because only limited site-level data had been collected. This means that researchers must still resolve the question of whether levels of caregiver consequences that cannot be explained by the data presented here are caused by cultural factors or by differences in mental health care provision. As long as cultural bias cannot be ruled out, researchers are advised to compose their own national norm groups and use these as a local standard.