Transform plate boundaries accommodate lateral plate motion and link the other two types of plate boundaries, generally juxtaposing lithospheres of different compositions and ages. These sites can generate major earthquakes and thus pose serious hazards. Oceanic transform faults are key elements in seafloor spreading whose behavior can be influenced by hydrothermal circulation and magma. Continental transforms are complex fault zones composed of multiple subparallel active strands. Fault bends, step-overs, and oblique plate motion result in transpression or transtension deformation. We welcome studies that advance our understanding of the initiation and evolution, structure, and dynamics of transform zones, including seismic and aseismic deformation, and especially encourage multidisciplinary studies that integrate seismology, geodesy, gravity, structural geology, geomorphology, geochemistry, rock physics, and/or geodynamics.