Grammar by Diagram, second edition is a book designed for anyone who wishes to improve grammatical understanding and skill. Using traditional sentence diagramming as a visual tool, the book explains how to expand simple sentences into compound, complex, and compound-complex sentences, and how to employ verbals (infinitives, gerunds, and participles) and other structures for additional variety.

The text addresses the most frequent usage errors by explaining how to distinguish between adjectives and adverbs; how to avoid problems of pronoun case, agreement, and consistency; how to ensure that verbs will agree with their subjects and will be appropriate in terms of tense, aspect, voice, and mood; and how to phrase sentences to avoid errors in parallelism or placement of modifiers. Six appendices incorporate further exercises, a summary of key basics from the text, and supplemental material not included in the body of the text but useful for quick reference. This new edition includes additional exercises and has been revised and updated throughout.