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; wherein selecting the particular target language translation based at least in part on the expectation maximum comprises: determining a first probability based at least in part on the particular target language translation during a first iteration; determining a second probability based at least in part on the particular target language translation during a second iteration; determining whether a difference between the first probability and the second probability is less than a specified threshold; in response to determining that the difference between the first probability and the second probability is less than the specified threshold, setting a final translation probability for the particular target language translation equal to the second probability; and selecting the particular target language translation based at least in part on the final translation probability; and wherein said steps are performed by one or more computing devices.