Abstract: The classic Dutch disaster-warning system (the 'siren') is not as effective as it should be. The alarm is not heard by 37% of the population, not all the people that hear the siren do take it seriously. A public-warning system was developed based on so-called 'intelligent SMS'. This system was tested in 2004 among 700 inhabitants of the city of Vlaardingen (region Rotterdam-Rijnmond). The University of Delft conducted an intensive evaluation. The evaluation shows that use of SMS is technically feasible. It diminishes the part of the population that is not reached is by approx. 50%. The public is now not only warned that 'something is going on' but is informed by SMS of the nature of the threat ánd on what to do. The public perceives intelligent SMS as the most effective warning system. Based on the pilot, the disaster-management authority of the region Rotterdam-Rijnmond, with some 1.2 million inhabitants, decided to structurally implement the system in the whole region in 2005.