The NanoMiX project has the ambition to establish a new expertise at the interface between nanophotonics and mesoscopic optics, by tackling the study of complex nanostructures, more specifically disordered ensembles of exotic, strongly resonating nanoparticles interacting efficiently between themselves via a layered substrate (e.g., thin-film stacks supporting guided modes). We believe that these “complex optical stacks” have a high scientific and technological potential thanks to the richness of their optical properties, coming from the individual nanoparticles, their interaction with the geometry and their mutual interaction via a controlled disorder. The NanoMix project aims to: (i) Develop the theoretical and numerical tools that will allow analyzing such multi-scale systems in their whole complexity; (ii) Develop new knowledge and concepts on mesoscopic phenomena in complex optical stacks; (iii) Learn engineering complex nanostructures to obtain new optical effects. This project – very exploratory – goes into many challenges of modern nanophotonics and mesoscopic optics, such as the control of light coupling/decoupling in planar nanostructures or the formation and engineering of localized optical modes in disordered media. Beyond the expected increase of knowledge, the obtained results could have important outcomes on technologies, such as the efficient use of light energy in photonic devices (photovoltaics, organic LEDs, …), the realization of surfaces producing new, targeted visual effects for interior design or augmented/mixed reality applications, or the enhancement of light-matter interaction for quantum optics or bio-sensing. NanoMiX is a “JCJC” project led by a young researcher who has a rare double expertise in nanophotonics and optics of disordered media, and aspires to develop this still-unexplored research topic by building up a new theoretical team at LP2N.