Beginning with the first workshop held in 2011 in Trier, Germany, this workshop aims at bringing together researchers whose interest includes rainfall simulation studies. Rainfall simulators are important experimental tools in hydrology and geomorphology studies and have been widely used both in the laboratory and in the field for accomplishing a wide range of research objectives and purposes. The literature reveals the existence of more than 250 different rainfall simulator setups that exhibit a significant diversity in the simulators’ type, sizing, form and operation methodologies, which have been developed and adapted to address specific research demands. This flexibility, which is usually seen as a major advantage, can also have several drawbacks, in particular numerous difficulties for comparing results and outputs obtained from different rainfall simulators studies, using different simulators’ designs.