In recent years, the relationship between prosody and syntax has been the subject of a considerable amount of work while the prosody-semantics interface has received less attention in the literature. However, any complete analysis of spoken language must account for those contributions to meaning which intonation and other aspects of prosody can make. In this paper, we focus on two such phenomena in English, the prosody-only indication of polar interrogativity in declarative questions and the so-called 'comma intonation' associated with non-restrictive relative clauses. Based on standard theoretical assumptions augmented with a more fine-grained view of the contents of the lexicon, we propose a formal treatment of the interactions between prosody, syntax and semantics, motivated by a strong commitment to modular specificity, that is consistent with LFG's co-description architecture. The revised architecture we posit situates the string at the heart of interface phenomena and offers a new perspective within the LFG framework not only on the interface between prosody and semantics, but also on the prosody-syntax interface.