In communication, language users frequently produce referring expressions with noun phrases at their centre (NP REs). Over the course of a communicative interaction, interlocutors’ use of NP REs tends to change: previous research has attested to speakers’ tendency to converge on linguistic forms – establishing routines (e.g. Pickering & Garrod 2004, 2005) – and to shorten their NP REs in the process (e.g. Clark & Wilkes-Gibbs 1986; Brennan & Clark 1996; Castillo et al. 2019). The present chapter investigates this shortening process and observes the structural changes in NP REs that accompany it. The study is based on data from an experimentally elicited corpus of spoken English consisting of conversational dyads producing repeated references to visual stimuli in a referential communication task. Interlocutors are indeed shown to shorten their NP REs over the course of the elicited dialogues: particularly, a decrease in longer clausal post-head elements is observed, while the use of only premodified NP REs and shorter phrasal postmodification shows a relative increase. These changes are indicative of shifts in the type of structural modification the NP REs contain: initially, speakers produce more clausal elements, which are associated with structural elaboration; later in the interaction, a decrease in clausal and relative increase in phrasal modification reveals structural compression (cf. Biber & Clark 2002).