Comparing data on offences known to the police in 37 European countries for the year 1999, this chapter shows empirically how the counting rules use to collect data for police statistics in each country affect the outcome of such statistics and constitute one of the main explanation of cross-national differences in levels of recorded crime. Thus, countries recording offences when they are reported to the police present higher crime rates than countries recording offences when the police have completed the investigation. The chapter also shows that comparisons of homicide rates should only be made using data for completed intentional homicide (i.e. excluding attempts).