Recent developments in single-phase High Entropy Alloys (HEA) and multi-phase Compositionally Complex Alloys (CCA) will be considered. In both cases, the alloys should fulfill the often used requirement for HEA ̶ consisting of several elements (in general > 4) that possess equal or nearly-equal atomic concentrations. All possible alloy families will be taken into consideration. A special emphasis should be given to the processing history, i.e. material manufacturing, heat treatment as well as sample preparation. All kinds of materials properties are of interest, with a particular focus on mechanical properties. Studies on phase stability, microstructure on all length scales, dislocation morphology, and diffusion in HEA and CCA are welcome. Appropriate submissions should include scientific and/or engineering factors dealing with property correlations, e.g. microstructure ̶ mechanical properties. Papers addressing unique or outstanding properties or phenomena that cannot be found in conventional alloys are particularly encouraged.