The emerald ash borer (EAB) invasion of North America has caused widespread mortality of native ash, and is threatening the native ash resources. As a consequence of its devastating impact, EAB has caught the attention of the scientific community, and several studies have focused on different aspects of the biology and behavior of this pest, including its interaction with host defenses. Here we present a review of the published literature on mechanisms of ash resistance to EAB, the understanding of which, despite starting from a tabula rasa, has achieved significant progress in the last few years.