Abstract
The effectiveness of police enforcement has been the subject of a series of recent studies in The Netherlands. These studies were concerned with the use of seat belts, speeding (outside urban areas) and drinking and driving. The purpose of the studies has been to compare and improve the effectiveness of different types of enforcement by means of small scale campaigns. Finally, attention is paid to the programme of integrated enforcement in the region of Leyden, which forms a combination of successful elements of police enforcement of four selected traffic rules: drinking and driving, speeding, the use of seat belts and the proper use of helmets by moped riders.