New challenges of cross-border crime have sparked Member States’ awareness ofthe need to work closely together. At the same time, policy makers are looking fora knowledge based system of effective and efficient policies, both for the prevention and the fight against crime. To do so, one will need quantitative data on the levels, structures and trends of crime, on the measures taken to prevent and fight crime, and where possible, international comparisons to evaluate the allocation of resources. Hence the recent attention given to the lack of European statistical data. In June 2007, the European Commission launched a tender for the development of an EU-level Offence Classification System, focusing on terminology, concepts and definitions used, in the field of crime statistics. This paper presents the results of preliminary research conducted during the preparation of a research proposal following the above mentioned tender. As the European Commission expressly stated that an EU reference instrument needed to be created based on the existing harmonised offence definitions, the preliminary research was limited to these harmonised definitions: the authors will therefore analyse the current status questionis of Substantive European Criminal Law. Chapter one and two, dealing with the origin of the definitions, will reveal that 63 offence labels are defined in 101 instruments, of which framework decisions are not the most important source. In the third chapter the authors elaborate on
the challenges and pitfalls related to the definitions themselves, before moving on to chapter four, in which the methodology to be used in the Study for the development of an EU level Offence lassification System is presented.