This book presents a three-part discussion of the causes and prevention of errors in foreign language learning with particular reference to English as a second language. The first part provides a survey of error analysis, defining what is meant by the term "error" and establishing a model of error production. Other terms explained in this section are communication, redundancy, prediction, probability, and interference. The second section provides a survey of errors attributable to perception of redundancy and discusses such specific items as noun groups, verb groups, pronouns, comparative, question forms, spelling, and pronunciation. The final section provides a commentary on errors attributable to interference and deals with mother-tongue interference in pronunciation, vocabulary, and syntax, as well as errors caused by analogical thinking and cross association; homonymy, homophony, homography, and polysemy are also considered. Concluding remarks concern the relationship between error production and learning motivation. (VM)