Melt crystallization processes are predominantly used to purify organic materials. An overview of the used techniques and patents of melt crystallization processes will be given. Special emphasis are given in this report to the layer crystallization processes. A comparison of the static and dynamic crystallization will be made with regard to the obtainable separation efficiency. On top of the separation by the actual crystallization process a further purification can be achieved by additional post-crystallization processes like washing or sweating. A model to predict the effectiveness of such operations will be presented. A new phenomenon, which has not been considered yet, is the migration of liquid inclusions in a crystal layer. This phenomenon does influence the resulting concentration profile in a crystal layer and the final purity of the layer to a notable extend. Finally new developments will be presented like a new continuous solid layer melt crystallization process or the current activities of the crystallization group in Bremen, Germany.