This paper investigates the processing of long-distance filler-gap dependencies in Japanese, a strongly head-final language. Two self-paced reading experiments and one sentence completion study show that Japanese readers associate a fronted "wh"-phrase with the most deeply embedded clause of a multi-clause sentence. Experiment 1 demonstrates this using evidence that readers expect to encounter a scope-marking affix on the verb of an embedded clause in "wh"-fronting constructions. Experiment 2 shows that the "wh"-phrase is already associated with the embedded clause before the embedded verb is processed, based on a Japanese counterpart of the Filled Gap Effect (Stowe, 1986). Experiment 3 corroborates these findings in a sentence completion study. These findings clarify the factors responsible for "active filler" effects in processing long-distance dependencies (Crain & Fodor, 1985; Fodor, 1978; Frazier & Clifton, 1989; Stowe, 1986) in ways not possible in head-initial languages. The results provide evidence that the processing of filler-gap dependencies is driven by the need to satisfy thematic role requirements of the fronted phrase, rather than by the need to create a gap as soon as possible. The paper also discusses implications of these findings for theories of reanalysis.