TESOL-Teachers of English to Speakers of Other Languages-is the acronym that refers to the professional association, the profession, and the field itself. Headquartered in Alexandria, Virginia USA, TESOL has more than 13,500 members from 140 countries. Its membership is a diverse mix of teachers, researchers, administrators, material writers, and curriculum developers whose primary focus is on enhancing English language learning, whether it is English as a second language (ESL) or English as a foreign language (EFL). TESOL's mission is to ensure excellence in English language teaching to speakers of other languages.