Nanoparticle assembly is a hierarchical approach to functional materials. It operates at the mesoscale where elementary building blocks still feel their atomic nature and can profit from quantum function but at the same time are flexible enough in shape and interaction to permit high structural complexity. The realization of nanoparticle assemblies requires the convergence of and communication among several scientific disciplines: chemistry for synthesis, materials science for characterization, chemical engineering for up-scaling, and physics for a theoretical description and quantum phenomena. The goal of the conference will be to provide a coherent view of the current state of the field, bringing together researchers with different expertise and background. It should catalyze the development of new methods, both theoretical, computational and experimental, and define the basic science in this field. A focus will be recent developments but also a look forward: What should be the focus for the next decade and beyond? What are they key physics concepts that need to be developed and from where will the new game-changing technological advances emerge?