Determining Language of Text Fragments

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for receiving content data, the content data comprising text, identifying an author of the text, the author being a user of a social networking service, retrieving data corresponding to one or more social graphs associated with the user, the data being stored in a computer-readable storage device, and determining the language of the text based on the data corresponding to the one or more social graphs associated with the author.