Research in the field of wide-bandgap (WBG) semiconductors has continued to expand in recent years. Nitride-based semiconductors have already led to a revolution in lighting, as visible light-emitting diodes are now commercially available for general illumination purposes and represent a fundamentally new and more efficient way for humanity to generate light. In addition, new architectures for light-emitting devices (e.g. nanowires and quantum dots) are being studied and optimized. However, material-related aspects may significantly limit the efficiency of all of these devices, e.g. by inducing defect-related recombination, by limiting light extraction efficiency, and by reducing device reliability. WBG materials have also greatly influenced radio-frequency (RF) electronics, and are now having a dramatic impact on power electronics. Based on SiC and GaN, it is possible to fabricate diodes and transistors with blocking voltages in the kV range with low on-resistance and fast switching, and such devices are rapidly being adopted in the next generation of low-loss power conversion systems. This in turn has, and will continue to have, a positive economic and environmental impact. However, there continues to be an urgent need for further materials innovations for RF and power devices. For example, several strategies are being explored for the fabrication of normally-off GaN-based transistors, but the stability and the reliability of the various solutions are still under debate; and the lack of native GaN substrates of large area and low cost limits the development of vertical transistors based on nitride semiconductors. Additionally, the "ultra" wide-bandgap (UWBG) semiconductors with bandgaps larger than 3.4 eV (including AlN and Al-rich AlGaN, Ga2O3, and diamond) are emerging as the next frontier in semiconductor physics. Numerous fundamental issues regarding these materials remain unresolved, and study is ongoing on areas such as bulk and epitaxial crystal growth, doping and defect physics, and electronic and thermal transport. Further, potential applications for UWBG materials span a broad range, including UV optoelectroncs, RF and power electronics, quantum information systems, and sensors. This symposium will broadly cover materials- and device-related topics important to the ongoing development of wide- and ultra-wide-bandgap semiconductors.