An adaptive machine translation service for improving the performance of a user's automatic machine translation system is disclosed. A user submits a source document to an automatic translation system. The source document and at least a portion of an automatically generated translation are then transmitted to a reliable modification source (i.e., a human translator) for review and correction. Training material is generated automatically based on modifications made by the reliable source. The training material is sent back to the user together with the corrected translation. The user's automatic translation system is adapted based on the training material, thereby enabling the translation system to become customized through the normal workflow of acquiring corrected translations from a reliable source.