Phase change materials (PCMs) exhibit remarkable properties that have led to groundbreaking applications and important advances in fundamental material science. By employing appropriate sub-nanosecond laser or electrical pulses, nanosized samples of PCMs can be switched rapidly between structural phases that display pronounced optical and electrical contrast. PCMs are successfully employed in optical data storage, including commercially available high-density re-writable DVD and Blu-Ray disks. Perhaps more importantly, high-speed non-volatile electronic memories based on PCMs are serious candidates to replace Flash memories. Phase-change random access memory (PCRAM) devices hold the promise of energy-efficient, nonvolatile storage that are capable of switching at DRAM-like speeds. Usually PCM devices exploit property contrast between crystalline and amorphous states, whilst switching between two crystalline phases was recently shown to occur in superlattice structures and disordered PCMs. PCM alloys are typically chalcogenides, but other, non-chalcogenide, materials such as GaSb are coming into play. The commercialization of PCRAM devices was a major milestone and now a number of challenges need to be overcome to ensure this exciting technology reaches its full energy and scaling potential. These challenges require further technological advances as well as a deeper understanding of the fundamental material physics. PCMs are also promising materials for a variety of other applications: these include active photonic devices, antennae, analog circuits, ovonic threshold switch (OTS) selectors and non-von Neumann-based devices, such as neuromorphic memories. Needless to say, these exciting developments pose new theoretical and experimental research directions. This symposium, initiated at the Spring 2006 Meeting, brings together the technological and scientific communities working on PCMs to identify: outstanding fundamental problems, present technological trends, and to highlight current scientific results and breakthroughs. The audience includes physicists, chemists, materials scientists, device physicists, electronics experts and process engineers. The inextricable link between outstanding technological problems and gaps in our understanding of the underlying physics of phase change materials make a symposium dedicated to phase-change materials a synergistic event.