This paper reports on an experimental study that investigates the acquisition of Japanese
unaccusative verbs by English-speaking learners. Following Levin and Rappaport Hovav (1995),
it is assumed that unaccusativity is syntactically represented but semantically determined. The
experiment is devised specifically to examine whether L2 learners are sensitive to syntactic and
semantic properties associated with unaccusative verbs in Japanese, which contrast with the
properties of unergative verbs. In particular, the experiment involved picture tasks with two
structures: the takusan construction as a syntactic test and the -teiru
construction as a semantic test. Overall results of the experiment show that L2 learners generally
know the properties investigated; that is, that subjects of unaccusative verbs originate in object
position, and semantic notions such as telicity and change of state are
aspects of meaning relevant to the classification of unaccusativity in Japanese. Based on these
results, it is argued that the mapping of verb arguments to syntactic positions is not random, but
rule governed, for most of the L2 learners in the present study.