This paper presents a unified approach to multiple nominative and accusative constructions in Korean. We identify 16 semantic relations holding between two consecutive noun phrases (NPs) in multiple case marking constructions, and propose each semantic relation as a licensing condition on double case marking. We argue that the multiple case marking constructions are merely the sequences of double case marking, which are formed by dextrosinistrally sequencing the pairs of the same-case marked NPs of same or different type. Some appealing consequences of this proposal include a new comprehensive classification of the sequences of same-case NPs and a straightforward account of some long standing problems such as how the additional same-case NPs are licensed, and in what respects the multiple nominative marking and the multiple accusative marking are alike and different from each other.