Many installations critical for military training and testing are located throughout the southwestern United States and provide essential habitat for numerous threatened, endangered, and at-risk species (TER-S). SERDP, ESTCP, and the Legacy Resource Management Program sponsored a workshop to (1) assess TER-S management needs within a regional context, with an emphasis on system-level and cross-boundary approaches; (2) assess these approaches for their potential to keep common species common while recovering or enhancing TER-S populations; (3) assess current understanding of the ecology of arid and semiarid ecosystems and how that does or should affect management approaches; (4) examine the current state of the practice within DoD for such holistic approaches; and (5) identify gaps in knowledge, technology, management, and partnerships that, if addressed, could improve implementation of such approaches. Discussions resulted in the prioritization of investment opportunities to address such gaps and management challenges. These opportunities are described in the Workshop Proceedings.