This study centres on the nature of vowel harmony in contemporary Korean within the framework of Optimality Theory (Prince and Smolensky 1993). The occurrence of vowel harmony is, however, very limited in contemporary Korean, only being found in: (i) ideophones, and (ii) some verbal morphology. Moreover, the phonological behaviour exhibited by the processes in question is very rare cross- linguistically. The present study attempts to solve these puzzles by regarding the vowel harmony of contemporary Korean, not as vowel harmony as such, but as a morphological process that manifests as pseudo vowel harmony. It will be argued throughout the dissertation that this view is decidedly superior to previous ones holding the existence of conventional vowel harmony in contemporary Korean.