The Defense Sciences Office (DSO) of the Defense Advanced Research Projects Agency (DARPA) is hosting a Proposers' Day Workshop that will provide critical information on the program vision, the program objectives, and opportunities associated with the development of an interdisciplinary proposal to respond to a Broad Agency Announcement. This solicitation is specifically for innovative multidisciplinary research proposals in the area of extended solids. The vision of the DARPA Extended Solids program is to: (i) identify high pressure material phases of molecular compounds that exhibit properties far superior to those currently available for DoD application(s), (ii) develop scalable processes that will permit access to these high pressure phases and ultimately bulk fabrication without having to go the ultrahigh pressures currently required, and (iii) develop methodologies ensure the stability of these materials down to ambient temperatures and pressures. Data obtained to date indicate that a number of these materials with extended high pressure phases exhibit superior structural (high strength, high thermal conductivity), energetic (propellant) and functional (e.g. ferroelectric, magnetic, optical) properties with the potential of concomitant performance improvements in a wide range of specific DoD applications ranging from armor to propulsion to aerospace, ground, and naval platforms. The Extended Solids Proposers' Day will introduce interested researchers to the details of the program, provide a forum to facilitate interaction, and encourage collaboration between researchers with expertise in relevant disciplines.