Interactions between fluids and fractures are fundamental to Earth and planetary processes ranging from the flow of ground water and contaminants, to the migration of natural hydrocarbons or sequestered carbon dioxide, to formation of joints or faults, hydrothermal flow and vein origin, and the emplacement of igneous intrusions. Likewise, understanding these interactions is critical to the design and implementation of subsurface processes including the propagation of hydraulic fractures, the control of injected carbon dioxide, or the containment of radioactive waste. The purpose of this session is to bring together investigators from hydrogeology, geomechanics, structural geology, rock mechanics, planetary sciences, and other relevant disciplines to review in a single forum the varied perspectives on fluids and fractures. We invite papers on field, laboratory, and theoretical aspects of how fluids affect fracture aperture and growth, how fractures control fluid storage and migration, and how these processes are coupled to one another or to other thermal, chemical, or biological processes. Applications relevant to deep underground experiments (e.g. DUSEL, Yucca Mountain, URL) are encouraged.