The compilation of the Helsinki Corpus of English Texts (HC) was initiated in the early 1980s and the corpus was completed and publicly distributed in 1991. Its size is c. 1.5 million words, and it covers the periods from Early Old English to the end of Early Modern English, i.e., to the beginning of the eighteenth century. The Corpus is structured chronologically and by sociolinguistic, dialectal and genre-based parameters. After two decades, it is still used in various parts of the world as a “diagnostic” corpus giving useful indications of the first thousand years of the development of the English language. The results given by the Helsinki Corpus can be easily supplemented from other larger and/or more focused historical corpora compiled in Helsinki and elsewhere.