Many theories of the internal structure of prosodic systems—and of the mapping between syntax and phonology—predict that there can be no prosodic head without a corresponding prosodic phrase. The English post-lexical pitch accent has the characteristics of a prosodic head but is not associated with any known prosodic phrase. Based on our knowledge of the prosodic hierarchy of English, a phrase headed by pitch accent would be larger than a word and smaller than an Intermediate phrase. This paper reports evidence of such a phrase, i.e., accent domain.