This book offers a contrastive, corpus-illustrated study of modal adverbs in English and Polish. It adopts a functional perspective on modal adverbs, and focuses on their interpersonal, textual, and rhetorical functions in the two languages. The items under analysis (e.g. certainly, probably, evidently, clearly) are categorised differently in Anglophone and Polish linguistics, which is why this book also provides some insights into the treatment of modality and modal adverbs in English and Polish studies, thus contributing to the discussion of the ways in which such concepts as modal adverb, modal particle, and discourse marker are understood across different languages and different linguistic traditions. It draws its examples from two monolingual corpora (the British National Corpus and the National Corpus of Polish), and the English-Polish parallel corpus Paralela.