Hard and soft particles strongly adsorb to liquid interfaces, leading to the formation of a two-dimensional crystal at the interface. The resulting particle arrangement is determined by the balance between attractive and repulsive forces of the interacting colloidal particles. While for hard spherical particles the capillary attraction generally leads to hexagonally close-packed monolayer at the air/water interface, soft microgel particles exhibit a more complex interfacial behaviour. They deform into a core-corona structure under the influence of surface tension at an interface. The interaction between these flattened coronae dominates the interfacial properties and the resulting phase behaviour. In the Vogel lab, we investigate this unique phase behaviour of microgels.