The ability to communicate effectively is considered to be the most important skill a police officer can have since written investigative reports are becoming more important in the courtroom and since proven effectiveness in written communication is increasing in importance as a prerequisite for promotion. The explanations and examples of those areas that cause the most problems were developed over a 2-year period in police cadet and freshman university English classes. An introduction to the language explains the use of words, letters, and numbers as symbols. The parts of speech, verb tense forms, word forms and functions, and sentence construction receive attention, followed by instruction in the three trouble areas of agreement, punctuation, and spelling. Suggestions are given for avoiding grammatical errors. Special sections are devoted to the writing of investigative reports, letters, and memos. Finally, a short essay explains the nature of good writing. Illustrations, grammar rules and appendixes containing a grammar quiz and 13 references are included.