A large number of participating countries in ICCS 2009 had also participated in the IEA CIVED study undertaken in 1999. The civic knowledge test included a sub-set of CIVED items which were used to derive comparable measures of civic content knowledge (one of the subscales used in CIVED) (see Schulz, Ainley & Fraillon, 2011). When comparing cognitive results it is important to take changes in test design as well as the equating error into account (see Monseur & Berezner, 2007). Some of the ICCS 2009 questionnaire material included items that were similar or even identical in wording to those used in CIVED but for which results have to be interpreted with caution due to general format changes. The first part of this paper describes the equating analyses and procedures undertaken for common cognitive items as well as European results across both surveys overall and for selected sub-groups (e.g. gender, books at home). The second part will discuss the possibilities of comparing questionnaire results between the two surveys in view of the format changes that were applied to the material. It will also include some selected results from European countries comparing perceptions among lower secondary students between 1999 and 2009.