Specific procedures for assessing young children's strengths and learning needs are described in this first volume of a 2-volume manual which describes a diagnostic method of teaching preschool children. An overall introduction to the manual is followed by Chapter 2, which presents the philosophical framework of the diagnostic approach and discusses the approach as it relates to major current issues in early childhood education. Chapter 3 provides a basic framework for diagnosis and assessment of the individual child and discusses general procedures for scheduling, conducting, and recording assessment. A sample form showing a child's diagnostic records is included. Chapters 4 to 8 present detailed procedures for diagnosing children's strengths and needs in the developmental areas of large motor, small motor and perceptual-motor skills; language; socio-emotional skills; and conceptual skills. General suggestions for helping children develop in each area are presented, and specific activities which are particularly useful in developing a given skill or teaching a given concept are listed. (These activities are fully described in Volume II.) Chapter 9 explains how to use the information obtained through diagnosis over the course of the year and how to plan a program that incorporates the strengths and needs of individual children and the total group. Chapters 10 and 11 provide practical ideas for use of space and equipment, staffing, parent involvement, and children's health and safety. (Author/CM)