This article argues that the data on English evidential markers indicate that evidentiality is not a grammatical category which is only applicable to some languages, but can be considered a universal semantic function that tends to trigger the grammaticalization of lexical forms. This study investigates five criteria that can help us locate linguistic forms on the lexicon–grammar continuum: reduction, desemanticization, backgrounding, decategorialization and paradigmatization. Although it has not reached the full maturity of so-called ‘evidential languages’, English provides evidence of the grammaticalization of evidentiality. Evidentiality is thus a relevant notion for English which substantially impacts the organization of the lexicon of the language, and the evolution of its grammar.