This will entail RF issues pertinent to X-band accelerating structures in linear colliders and light sources. In particular, RF fields in structures and cavities, wakefields, RF couplers and beam dynamics issues will be explored. The workshop will also embrace both active and passive overmoded and quasi-optical components Accelerating structures, light sources and drive beams will be amongst the areas of interest. A series of invited plenary talks will be given in addition to contributed topics. This will also include breakdown issues pertinent to high gradient structures, but the focus of the workshop will be on RF and impedance issues both from both a theoretical and experimental perspective. Papers submitted will be published on the JaCoW database.