This chapter provides an Element phonology-based description of the oral vowels of European Portuguese (EP). We propose that a 9-underlying segment inventory (/i e ɛ a ɔ ο u ɐ ɨ/) describes comprehensively the oral vowel system of this language. Such inventory corresponds to the phonetic inventory of oral vowels found in the standard variety of EP, albeit not in a one-to-one correspondence. Following the rationale proposed in this chapter, the lexical representation of each phonetic vowel must be examined taking into consideration the lexical and grammatical conditions of its occurrence. With regard to mid vowels, a lexical difference between close-mid and open-mid is accepted when lexical contrasts between unrelated words rely on/e/vs./ɛ/and on/ο/vs./u/solely. When phonetic realizations [e], [ɛ], [ο], and [ɔ] are the result of morphophonemic alternation, we interpret them as phonetic counterparts of differently specified vowels or of underspecified/E/or/O/. Following a similar line of argumentation, it is also proposed that [ɐ] and [ɨ] correspond to underlying/ɐ/and/ɨ/, respectively, when lexical contrasts depend on these oppositions, or to/a/,/e/,/ɛ/,/E/, when they alternate with [a], [e], [ɛ], or [ɨ]. We also reiterate that the unmarked vowel of European Portuguese is/ɨ/. A close look at Unstressed Vowel Reduction—commonly assumed as the main phonological process affecting oral vowels in EP—suggests: (1) a possible ongoing change in the phonological system, whereby reduction has been progressively losing productivity; and (2) that Unstressed Vowel Reduction might correspond to two different processes, in view of the different behavior of palatal vowels (which undergo bleaching and sonority reduction) and of labial vowels (which show coloring and contrast enhancement). General remarks about vowel nasalization and glidization are given in the final remarks.