The thesaurus is intended as a preliminary standardization and clarification of terms used to index special education instructional materials throughout the Special Education Instructional Materials Centers/Regional Media Centers (IMC/RMC) Network. The majority of entries are approved descriptors appearing in the selected standard, the Thesaurus of ERIC Descriptors. Other entries are identified as terms which are not approved descriptors of the Educational Resources Information Center (ERIC) thesaurus but which represent concepts necessary to the indexing of instructional materials. Over 400 indexing terms are included. Related terms are cross referenced and selective usage notes are provided. (KW)