The volume is a selection of papers presented at the International Conference on Foreign Influences on Medieval English held in Warsaw on 12-13 December 2009 and organized by the School of English at the Warsaw Division of the Academy of Management in Łódź (Wyższa Szkoła Przedsiębiorczości i Zarządzania). The papers cover a wide range of topics concerning the impact of Latin, Scandinavian, French and Celtic on Old and Middle English from orthography, morphology and syntax to lexical semantics and onomastics.