According to the Unaccusativity Hypothesis, unaccusative subjects are base generated at the object position, and move to the subject position. We examined this hypothesis using a Cross Modal Lexical Priming technique, which enables the examination of whether and when an antecedent is reactivated during the on-line processing of a sentence. We compared sentences with unergative verbs to sentences with unaccusatives, both alternating and non-alternating, and found that subjects of unaccusatives reactivate after the verb, while subjects of unergatives do not. Alternating unaccusatives showed a mixed pattern of reactivation. The research directly supports the Unaccusativity Hypothesis.