This synthesis reviews current knowledge of pinyon and juniper ecosystems, in both persistent and newly expanded woodlands, for managers, researchers, and the interested public. We draw from a large volume of research papers to centralize information on these semiarid woodlands. The first section includes a general description of both the Great Basin and northern Colorado Plateau. The ecology section covers woodland and species life histories, biology, and ecology and includes a detailed discussion of climate and the potential consequences of climate change specific to the Great Basin and Colorado Plateau. The history section discusses 20,000 years of woodland dynamics and geographic differences among woodland disturbance regimes and resilience. The ecohydrology section discusses hydrologic processes in woodlands that influence soil conservation and loss; water capture, storage, and release; and the effect that woodland structure and composition have on these processes. The final section, restoration and management, covers the history of woodland management, the different methods used, the advantages and disadvantages of different vegetation treatments, and posttreatment vegetation responses. We also discuss successes and failures and key components that determine project outcomes important for consideration when restoring ecosystem function, integrity, and resilience.