In Chapter 2, Rémi Beguin, Yves-Henri Faure and Pierre Philippe describe the contact erosion process, where particles of a fine soil are pulled by a water flow through a coarse zone in contact with the fine zone. Such interfaces between two soils of different grain sizes are frequently encountered in real earth embankments where the occurrence of contact erosion is consequently suspected. At the sample scale, the threshold and the kinetics of contact erosion can be quantified due to specific devices in two configurations and with either cohesive or non-cohesive fine soils. At the large scale, scenarios can be identified to describe the consequences of contact erosion on overall behaviour and integrity of an embankment structure based on several full-scale tests.