This workshop will focus on mathematical methods for systems that involve multiple length/time scales and multiple physics. The complexity of structure and phenomena of these systems gives added importance to mathematical results. In addition, mathematics provides an additional approach towards devising computational strategies for handling multiple scales and multiple physics. Examples include continuum limit of atomistic models, hydrodynamic limit of interacting particle systems, heterogeneous multiscale methods, adaptive model refinement, and many other methods. This workshop will bring together researchers from PDEs, analysis, mathematical physics, numerical analysis, and scientific computing to address the difficult challenges that are presented by these issues.