This teaching guide emphasizes a practical approach to the individualization of reading instruction in elementary classrooms and offers suggestions for implementing diagnostic reading instruction. Diagnostic reading instruction requires that reading lessons and independent activities be planned from an analysis of students' strengths and weaknesses in reading skills. Sections in the guide discuss a definition of diagnostic reading instruction; how to write a skills array; how to evaluate initially student skills, including ways to construct an initial test battery, determine readability levels, and prepare criterion referenced tests; how to evaluate students during the school year; how to keep records; and how to organize flexible groups. (MKM)