Psycholinguistic research has shown that sentence processing is incremental (e.g., Altmann & Kamide, 1999). In Japanese, a verb-final language, native speakers use case markers to incrementally assign thematic roles and predictively activate a structural representation of upcoming linguistic items. This study examined whether second-language learners of Japanese, guided by case markers, generate predictions as to whether the upcoming verb involves the active or passive voice. The results show that the native speakers made predictive eye movements before the verb, but the learners did not; the learners were less efficient in using case-marker cues than the native speakers and relied more on verb morphology information. These results suggest that case markers guide thematic role assignments, expediting the processing for Japanese native speakers. Learners may depend more on information from the verb to compensate for the inefficiency in case-marker-driven predictive processing.