Learning academic English is probably one of the surest, most reliable ways of attaining socio- economic success in the United States today. Learners cannot function in school settings effectively without it. This variety of English entails the multiple, complex features of English required for success in public schooling and career advancement. It involves mastery of a writing system and its particular academic conventions as well as proficiency in reading, speaking, and listening. Unfortunately, academic English has often been ignored or under-emphasized in public school instruction. Many have not understood its importance in helping students function in school settings or have misunderstood its complex nature. This paper discusses approaches to the study of academic English and presents a multi-dimensional framework for analyzing it. The dimensions include linguistic, cognitive, and socio-cultural/psychological ones. The paper also describes the relationship between the English used in everyday situations and in academic ones. It concludes with a brief discussion of research implications pertaining to instruction, assessment, and professional development.