1. A computer-implemented method comprising steps of: training a source language text classifier based on labeled training data that is composed in the source language, thereby producing a source language model; translating source language features from the source language model into a target language, thereby producing a target language model; and applying a target language classifier, which uses the target language model, to a particular document that is composed in the target language, thereby determining whether the particular document belongs to a particular class; wherein the source language classifier determines, based on said training, whether documents composed in the source language belong to the particular class; wherein translating the source language features comprises automatically selecting, for a particular source language feature of the source language features, a particular target language translation of a plurality of possible target language translations of the particular source language feature; wherein selecting the particular target language translation is based at least in part on an expectation maximum; and wherein said steps are performed by one or more computing devices.