The domains of Teachers of English to Speakers of Other Languages (TESOL) are those spheres of concern involving persons who speak languages other than English or dialects of English other than the standard. This clientele has been classified traditionally in terms of programs in English as a foreign language, English as a second language, English as a second dialect, and bilingual education. This paper suggests a classification of these various groups by a configuration which differentiates yet relates them to each other by placing them along a continuous line running from one extreme, that of the non-English speaker, to the other extreme, that of the speaker of standard English. It is suggested that each program is an individual operation distinguished from others by variables such as student population, motivation, and teaching and administrative personnel. It is noted that heretofore methods and materials developed principally for one group (English as a foreign language) have been used for populations in various programs, and it is suggested that the TESOL organization should encourage research in linguistics, sociolinguistics, and psycholinguistics which will perhaps aid in the development of new strategies of teaching for all the programs which exist in the TESOL domains. (Author)