The verbal prefix meN-in Malay is known to block DP movement. The existing analyses of this phenomenon focus on the blocking effect of meN-in transitive sentences but have not paid attention to whether such an effect holds in intransitive sentences. In this paper, we examine the blocking effect of meN-in intransitive sentences and show that, surprisingly, meN-does not appear to block DP movement in sentences that are usually considered unaccusative. We propose that no blocking effect is found in intransitive sentences because all intransitive meNsentences are unergative. We present a hypothesis of the relation between verb meaning and sentence structure that accounts for meN-'s effect on verb syntax, making use of the notion of telicity and the distinction between ''internal'' and ''external'' causation. Our analysis implies that both lexical specification and structural determination are involved in determining the unergative/unaccusative distinction.