he present book is a comparative study of argumentative texts in English written by English newspaper writers and Polish advanced learners of English. It provides a description of lexical and grammatical features of the interlanguage of Polish learners and offers pedagogical recommendations based on selected patterns of overuse and undenise. The book also examines how text-based computer software can enhance general foreign language instruction. The first chapter of the book introduces the basic notions of corpus research and compares them with those of traditional linguistics. Chapters two, three and four are practical applications of corpus techniques to the relevant argumentative texts. In chapter two Biber's (1988) multidimensional model is used; in chapter three an analysis of phrasal complexity is performed; in chapter four, word and word cluster frequencies are examined.