Described is the diagnostic teaching model developed by the Illinois Regional Resource Center to provide assessment and programing for children with unexplained handicaps. The model is explained to involve a multidisciplinary approach and to include six basic components: referals, information gathering, diagnosis, prescription, consultation, and followup. Listed among the steps to be taken in assuring success in the acquisition of comprehensive information are determining the type of information needed, determining who must be contacted to acquire such information, and keeping a record of the information received as soon as it arrives. Guidelines to consider when selecting diagnostic measures are offered; and examples are provided for reporting results of motor, sensory/perceptual, speech/language, academic, social/emotional, and self-help assessment. Examples are provided for implementing the following components of prescription planning: long-range objectives, behavioral objectives, time frame (schedule), current performance data, alternative teaching strategies, motivational strategies, and environmental strategies. Principles for implementing followup are outlined which include presenting the teacher with simple, but explicit instructions; assisting in the selection and design of appropriate instructional materials; and involving the receiving teacher in the diagnostic/prescriptive process. Sample forms are attached. (SBH)