This is a practical handbook covering an area of grammar which up to now has not received systematic attention in textbooks for teachers and students of English: the structure of clauses and sentences and how these are built up and linked together. On the basis of an extensive analysis of students' writing, the author provides a classification of the most common structural mistakes and ambiguities which result from an inadequate grasp of how the elements of a sentence fit together. The source of each type of error is explained and extensive and varied exercise material on the problem areas is provided. The sentences used in the text are authetic examples taken from textbooks and newspapers or from the written work of students themselves.This handbook will be useful not only for non-native-speaking learners but also for native-speaking students and teachers of English, who will find it a helpful starting text on syntax at sentence level. Since answers to the exercises are provided, the book may be used both in the classroom and for self-study purposes.