|Abstract:||This paper investigates a long-standing issue of Korean consonantal phonology, namely the alternation between lateral [l] and flap [r]. Onset [l] in geminates has been problematic for the well-known onset-coda distinction, and has been accounted for by geminate inalterability (McDonough 1995). In this paper, I propose a set of new constraints governing liquid distribution whereby lateral [l] is licensed in moraic positions and flap [r] appears in non-moraic positions. Data are drawn from native Korean and loanword adaptations. The moraic approach proposed here explains the liquid distribution without recourse to the controversial geminate inalterability, and furthermore clarifies the distinction between native phonology and loanword adaptations. The variation within loanwords is also explained in line with the core-periphery structure of the lexicon advanced in Ito & Mester (1995).