This is a field guide I wrote that provides identification keys for all known cultivated Eucalyptus (and other species in the Myrtaceae family) on the planet. It is based entirely on morphological features to commonly and widely cultivated eucalypts. The key includes 173 taxa: one species of Angophora, nine species of Corymbia, and 163 species of Eucalyptus. I gathered evidence for cultivation from accounts in the literature, herbaria, personal communications, and observations of living trees in cultivation in Europe, North America, Africa, and Australia. The locations, prevalence of cultivation, and naturalization of several eucalypt species are discussed in this guide.