This thesis investigates how phrase structure of sentences is mapped onto phonological representations. The bare mapping theory is proposed which interprets syntactic boundaries as phonological boundaries. Prosodic phrases are formed by deleting a number of boundaries according to the level of phrase and the rate of speech. This theory supports the idea of bare phrase structure rather than X-bar theoretic phrase structure. The theory of cyclic Spell-Out enables us to do away with the readjustment rule. The effect of edge parameter is derived by syntactic head parameter. Optionality of phrasing is also explained by the deletion of a number of boundaries. Further consequences of the theory are discussed which include the effects of constituent length, i.e. secondary phrasal stress and Heavy NP Shift in English and optional phrasing in Korean and Japanese. The theory offers an alternative analysis to the Early Immediate Constituent analysis (Hawkins 1994) and help us to explore the relation between phrase structure and sentence processing. Prosody and punctuation in English and Japanese, topic/focus and phrasing, semantics and phrasing, and derivation and parsing are also discussed.