This document summarizes research on using mobile devices to support teaching English as a second language. It discusses how technologies like personal digital assistants (PDAs), iPods, podcasts, and cell phones can be used for language learning activities. The document reviews literature showing that these mobile devices allow learners to access language learning materials anywhere and anytime, and to complete listening, speaking, and writing exercises to improve their English skills. It also discusses some of the advantages and disadvantages of different mobile learning approaches that have been studied.