The existence of obligatory adjuncts in both predication and modification constructions is best understood as following from general conversational pragmatics, rather than from grammatical factors. In the case of clausal predication, adjuncts are used to satisfy the often-cited requirement that every utterance have a focus that serves to convey new information in the discourse; adjuncts are just one of several ways in which the focal requirement can be satisfied. We argue that as a pragmatic constraint, the focal requirement is derived from Grice’s maxim of quantity or Horn’s R-principle. This allows us to account for the fact that while utterances do normally require a successful focus, there can be certain principled exceptions. The appeal to conversational maxims also allows us to account for the appearance of obligatory adjuncts within nominal modification structures, in which focus is not the relevant notion.