Methods, systems, and apparatus, including computer program products, in which an input method editor receives graphemes in a first writing system and identifies lexical items in a second writing system based on the graphemes in the first writing system. In one implementation, a method is provided. The method includes receiving a first grapheme in a first writing system; using a grapheme graph of graphemes in the first writing system to identify a first n-gram representation in the first writing system of a first morpheme in a second writing system; using the first n-gram representation to locate one or more first nodes in a morpheme graph; selecting a first lexical item from the one or more first lexical items based on a first score associated with each of the one or more first lexical items; and providing the first lexical item for display on a user device.