We address the problem of integrating the description of discourse particles and their intonation into an HPSG--based lexicon for spontaneous speech applications, and propose a lexical sign type called prosody-- particle pair which has similar structure to grammatical inflexions and is formally described as a nested attribute-value structure. In our discussion we generalise a known class of `stylised intonations' to include the level intonation of hesitation particles. Previous descriptions of discourse particles, their roles and their relations to intonation, have been informal. Our proposal is the first to model particle-- intonation relations explicitly and in detail as an inflexion--like complex sign in a formal lexicon. The inclusion of the intonation of hesitation phenomena in the class of stylised intonations on formal and functional grounds is also new.