The following alternative analyses of the Korean vowel system are compared: (1) By the view of traditional phonemics, we recognize nine vowels /i e ø ε ə a u o/, plus autonomous /w y/. (2) By distinctive feature analysis, regarding w and y as on-glide realization of features [+round] and [+palatal], we recognize nineteen vowels: i e ε i ə a u o, wi we (= φ) wε wa wə, ve vε və va vu vo. (3) By the view of generative phonology, we recognize four vowels—high , low a, mid rounded o, and mid unrounded ə—with w and y as on-glides, and with y as a fronting off-glide. (4) If we extend the analogy of off-glide y, and recognize a backing off-glide w, then we have three vowels, ə a, and two distributionally free glides, w and y. It is argued that alternative (3) gives us the truest and simplest picture, when considered in conjunction with morphophonemic phonomena, and especially in the light of the generality that several phonological rules gain by this analysis. It is hoped that this paper illustrates the possibility of choosing the ‘descriptively adequate’ solution from among several competing, non-unique, ‘observationally adequate’ solutions.