The clearance rate consists of the number of cases in which at least one suspect is apprehended divided by the total number of recorded crimes. The reliability of the clearance rate as a measure of police effectiveness was analyzed by using 1999 data from the two main Dutch sources of police data, the CBS police statistics and the HKS data. Because of insufficient data, 7 of the 25 police regions were not included in this analysis. The analysis of the data and the procedures for collecting and recording them found flaws that make clearance rates an unreliable method for measuring police effectiveness, particularly across jurisdictions. For the clearance rate to be a useful measure of police effectiveness, varying definitions of clearance, incorrect recording, and the failure to link clearances to particular recorded crimes must be addressed. In comparing the crime clearance rate in the Netherlands with other countries, it was found to be lower in the Netherlands than in any other comparison country. Two external factors help explain this finding. First, the higher the percentage of crimes reported by victims to the police, the higher the proportion of cases that will be difficult to solve, which means a lower clearance rate. Second, a higher proportion of violent crimes, which are more likely than other types of crime to be solved, could result in a higher clearance rate. There are also differences in definitions and counting methods that influence the clearance rate. If the measurement of clearance rates can be standardized and interpreted properly across offense types and crime-reporting levels, then it can be a useful measure of police effectiveness in the future, but only if used in combination with the offender rate and the punishment rate. Each of these three measures have advantages and disadvantages. International comparisons of police effectiveness are likely to continue to be problematic due to major differences in criminal justice systems and crime-related definitions and data collection. 15 tables and 25 references