The mesoscale is the length scale spanning the nano (~10 nm) and the micro (~10 μm). It is here that collective/ensemble effects and the functionality critical to macroscopic phenomena emerge but generally cannot be described by the behavior of atoms and molecules alone. At the mesoscale, nonlinearities, defects, interfaces, and non-equilibrium structures are common and collective interactions can result in novel emergent properties. Mesoscale materials are often synthesized by the assembly of molecular or nanoscale building blocks. Examples include nanocrystal solids, optical metamaterials, micelles/membranes/capsids, and composite biomaterials. The inaugural UC Mesoscale Materials Summer School held August 9-10, 2018 at the University of California, Irvine will bring together students, postdocs, and established experts in the field for two days of science seminars on self-assembly, characterization, and modeling of mesoscale materials, short courses on key characterization and measurement techniques, and career development activities for graduate students, postdocs, and early-career researchers. Please join us.