In recent years, the mountain pine beetle, Dendroctonus ponderosae, has impacted 8.9 million hectares of forests in the western United States. Historically a common occurrence in western forests, particularly in lodgepole and ponderosa pine, the magnitude and extent of recent outbreaks have exceeded past events since written records are available and have occurred in areas where outbreaks were less common. While mountain pine beetle is an important part of the ecology of these forests, extensive levels of tree mortality resulting from outbreaks may have undesirable impacts, for example negatively affecting aesthetics, recreation, and fiber resources among other ecosystem services. This special section contains 10 articles concerning different aspects of the biology, ecology, and management of mountain pine beetle. A number of relevant topics are reviewed and available literature synthesized.