A collection of seven essays on errors in second language learning focuses on secondary school instruction in the United Kingdom. The essays address three questions that a foreign language learner might ask the teacher, including: What do you mean, it's wrong?; What do I have to do to make it better?; and Why should I get it right anyway? The first question requires the teacher to define a defective performance, and the second asks what action is to be taken to improve the performance. The third question arises from the communicative competence approach, suggesting that grammatical mistakes should not affect communication. The papers are: "Mistakes Are the Mistake" (Keith Morrow); "The Concept of 'Duly Performed'" (Stella Marsh); "The Many Sorts of Error" (Richard Beaton);"Learner Autonomy" (Rosemary Olivier); "GCSE Assessment Criteria and Their Messages for the Learner" (Brian Page); External and Internal Assessment: A Discussion of Two NFER Projects" (Peter Dickson); and "Why Do I Have To Get It Right Anyway?" (Brian Page). (MSE)