The IJkdijk project is an international test site for inspection and monitoring techniques for levees. The objectives are two-fold: firstly, to develop and validate new sensor techniques and secondly to perform full-scale failure experiments on levees to understand fundamental behaviour in order to be able to increase the quality of the inspection process and safety assessment of levees. The final goal is to be able to respond timely with appropriate measures. The experiment that will be focused on in this paper is a stability test. In the beginning of 2008, a preliminary full-scale test has been performed to determine the characteristics of the subsoil in the area. The results of this test are needed to optimize the full–scale, heavily monitored levee stability failure test, which is executed in the end of 2008. The full-scale tests also have been simulated on a much smaller scale in centrifuge tests. The paper illustrates the applicability and benefits of modern sensor technology by one of the measured parameters, the horizontal deformations. They seem to indicate trends, already hours before failure occurred and may thus act as an early warning system…