Since Perlmutter (1978) proposed the Unaccusativity Hypothesis, the past two decades have seen a flourish of studies investigating the potential validity of unaccusativity in Korean. The central contentious issues have been whether unaccusativity can also be assumed in Korean, and, if so, what criteria could be proposed to discern the unaccusativity among various predicates. In this paper, several suggestions made theoretically and experimentally to address the semantic and/or syntactic distinction of the two types of Korean intransitive predicates are critically reviewed and evaluated from the standpoint that there is a close correlation between syntax and lexical semantics of intransitives. It is proposed, then, that the Korean unaccusativity can be reliably differentiated through the combined semantic criteria of [${pm}$agentive] and [${pm}$active]. In addition, case alternations in long form negation constructions are shown to be the most reliable and valid syntactic criteria for testing Korean unaccusatives.