The functions of sure in British and American English are relatively well known. Sure is used as a backchannel and an agreement marker similar to yes (Aijmer 2009; Tottie 1991). Its emphasizer function in lexical bundles of the type ‘(NP) sure + AUX’, as in He sure is an odd fellow has also been cited as a marker of Americanness (Aijmer 2009; Tottie 2002). Additionally, Aijmer (2009) suggests that sure developed as follows: manner adverb > epistemic adverb > interactive discourse marker. A very different type of sure, usually in utterance-initial and -final position, has been attested for Irish English (cf. e.g. Amador-Moreno 2006; Walshe 2009). Its functions, however, are not yet well understood.This paper offers an original account of Irish English sure as a discourse marker similar to after all (Blakemore 2002), Hebrew harey (cf. e.g. Ariel 1998, 1999) and German ja and wohl (Blass 2000). The data (audio recordings and the ICE-Ireland corpus) show that sure is phonologically reduced, semantically bleached, and multifunctional. On different occasions sure-utterances can indicate a contradiction or strengthening of a previous assumption, or a premise to a conclusion. It is suggested that these multiple functions should be understood as different conversational implicatures which regularly attach to sure. These are all aided by its basic, procedural meaning. Sure indicates that the material under its scope is considered by the speaker to represent relevant contextually accessible information against which a contextual implication can be drawn.