System and methods allowing for effective and reliable reading predictions for Japanese ideographs are provided. In an illustrative implementation, a reading predictions system operating in "learning" and "execution/run-time" modes is provided. In the "learning" mode the reading predictions system operates on a number of input sources to produce a decision tree that is used in the "execution/run-time" mode to return reading predictions for inputted Japanese sentences containing Japanese ideographs. Among the inputs utilized in the "learning" mode are base Japanese script readings, a training corpus, and quasi-phonological rules. From these inputs underlying readings and a decision tree are created. When operating in the "execution/run-time" mode, the reading predictions system employs a morphological analyzer to perform a morphology analysis on inputted sentences. Using the morphological analysis, the quasi-phonological rules, the underlying readings, and the decision tree reading predictions are provided.