M-dwarf systems provide several compelling motivations for study.  M-dwarf stars are the most numerous, evolve slowly on the main sequence, and are the most amenable targets for detecting and characterizing extrasolar planets.  Furthermore, planets within the habitable zone of M-dwarf stars will be tidally locked.  This feature imposes a profound control on planetary climate.  The planetary rotation rate, incident stellar flux, and spectral energy distribution become inextricably linked by the orbital configuration of the system.  Atmospheric dynamics, convection, clouds, and shortwave absorption by water vapor all are fundamentally affected.