The study of pragmatics examines the mechanisms underlying speakers' ability to construct meaning in context and hearers' ability to infer meaning beyond what a speaker has explicitly said. These abilities are taken to depend both on the properties of what is said as well as on considerations of what isn't said. In this talk, I present a series of psycholinguistic experiments that highlight how the context of alternatives provides knowledge that is brought to bear on pragmatic inference. The first set of studies asks how one pragmatic phenomenon, referential communication, is influenced by properties of competing forms. The context of alternatives is shown to guide *how* speakers refer (probabilities for choice of referring expression); however, there are other coherence-driven cues that capture *who* speakers are likely to refer to (prior probabilities over choice of mention). Listeners in turn can be understood to combine these probabilities to estimate the likely referent of an ambiguous expression, as predicted by a Bayesian model of coreference. What is most intriguing about the data is the apparent independence of contributions from factors related to message meaning (implicit causality, coherence) and those related to message form (production cost, information structure). Another domain where competing forms guide communication is in the use of focus marking. Results from a set of comprehension studies show how focus marking evokes alternatives and thereby influences several pragmatic phenomena.