Multiscale and multiphysics methodologies have become an integral part of molecular modeling and simulation and have been applied to various real-world problems that would have been out of reach without scale-bridging techniques. Two examples of currently active research areas are (1) enhanced sampling methods, such as Parallel Replica or Metadynamics, that have been successfully used in, e.g., material science or bimolecular conformation dynamics, even though they are lacking a rigorous theoretical foundation , (2) coarse-graining methods for complex liquids as for example the popular Mori-Zwanzig projection operator formalism . Such methods are physically relatively well-founded (and mathematically justified for particular cases), but are often difficult to apply to any realistic system. The focus of the meeting will be a critical discussion of some of the most popular methodologies in the field, that involve either multiple scales (in space and time) or heterogeneous coupling between different models (e.g. discrete and continuum models). While the methods in the field have their merits (as is reflected in the large number of publications and conferences), there is no systematic account of their conceptual deficits or computational limitations (which is also reflected in the lack of corresponding literature or scientific meetings). Not only do we believe that the critical appraisal of some of the most prevalent scale-bridging techniques is necessary to assess both the reliability of computer simulations and the used models, but we also expect that the critical discussion will offer new research directions and stimulate exactly those collaborations among practitioners and theorists that are needed to tackle current challenges in molecular simulation.