This study rethinks an old issue concerning the generation of the allomorphs of the English past tense suffix -ed. Based on historical and synchronic data, it is proposed that the underlying phonological representation of the suffix should better be /əd/ and the schwa gets deleted in the generation of the surface representation under phonological conditions. Given the proposal, the historical development of the suffix can be incorporated into the new account, and the spelling of the past tense suffix, which is highly connected with the phonological information of the suffix, is accounted for as well. This proposal thus implies that the English past tense suffix is generated through a different phonological process from the plural suffix and the third person singular present tense suffix.