An attempt is made in this book to make teachers aware of some informal techniques which can be used to diagnose strengths and weaknesses in the language arts abilities of students. The techniques are economical in the use of time but are fairly comprehensive in the information gathered. They have been tested and refined by more than 1,000 preservice teachers working with children in a tutorial situation over a period of ten years. Part one begins with a summary of basic information in the language arts. The chapters which follow present comprehensive discussions on oral language, listening, handwriting, spelling, and written language. Part two presents diagnostic techniques in the language arts, with specific diagnostic check sheets in oral language, spelling, handwriting, and written language. Part three deals with instructional techniques in the language arts and includes discussions on managing instruction and on implementation of diagnostic teaching, as well as case studies which provide better understanding of diagnosis, program planning, individualization of instruction, and evaluation of both the program and the teachers. An appendix presents a list of materials and equipment. (LJR)