To be about to: Approaching the ‘irrealis’ Paloma Tejada Caller. Universidad Complutense Madrid. Abstract: The purpose of this article is to describe the gradual grammaticalization process undergone by about during the Early Modern English period and its conventionalization as a temporary evidential/epistemic marker. As suggested by the corpus of examples of actual use collected from the Helsinki Corpus of English Texts for the period 1350-1640, this marker seems to move from a more basic notion of immediacy and indefinite location into the realm of evidentiality/ epistemicity through the idea of appearance or resemblance. From this standpoint, it offers a neutral, objective, non-precise description of reality as sensorically or mentally perceived by the speaker, implicitly qualifying events as merely potential. Though further research is needed, crosslinguistic and evidential-like parameters prove useful to get a better knowledge of the semantic substance of particular markers and allow new tentative explanations of non-linear linguistic evolution. Keywords: diachrony, cognition, epistemic modality, evidentiality, grammaticalization Introduction Present Day English grammars (Quirk et al. 1972, Quirk et al. 1985, Jespersen 1933, Leech & Svartvik 1975, Long 1966, Schibsbye 1970, Willis 1972, Woods 1990, etc.) conventionally describe the expression to be about to as a semi-modal auxiliary indicating future unconditioned highly probable event. As such, it participates in a half-closed category of semi-fossilized expressions, not fully modal in their syntactic or semantic behaviour, and often closer to the tense-aspect system. However, diachronically things may have been different. It is generally accepted that today’s fossilized structures integrate into regular, consistent systems of the past linguists have only to reconstruct (Smith 1996). The purpose of this article is to propose the gradual grammaticalization of about during the Early Modern English period and its conventionalization as a temporary evidential/epistemic marker, washed away into different and apparently disconnected structures in subsequent stages of the language, one of these