This paper wanted to test the reality of English schwa by phonetic and phonological methods. Phonetically it wanted to see acoustic evidence of the relationship between the full vowels and their reduced vowels in the unstressed positions. Phonologically it wanted to prove how systematic the schwa sound is by the constraint-based grammar. As a result, the schwa phenomenon in English was supported both phonetically and phonologically. In the phonetic analysis no relationship Was found in the distribution of the F1 and F2 of the full vowels and their reduced vowels in the unstressed syllables of the derived words. The reduced vowels tended to converge into a target of F1 516 and F2 1815. The view that the schwa sounds have a target was supported. On the phonological side the constraint-based tableau produced the successful output by using FAITH (V), (equation omitted)V, FAITH V[-BACK+HiC], V[-Low, -TNS]#, REDUCE V[-STR, -TNS] as constraints. No ranking was found. Any violation of the constraints ousted the candidates.