This document discusses using mobile apps to enhance vocabulary development for adult English language learners. It provides an overview of effective vocabulary instruction practices, including teaching individual words, word learning strategies, providing varied language experiences, and fostering word consciousness. Mobile apps can support vocabulary learning in several ways that address these practices, especially by creating opportunities for independent language use and exposure. The document then recommends specific dictionary, flashcard, and book apps that are available for smartphones and tablets to help students learn vocabulary on the go. It concludes that these tools can provide language learners with easy access to resources like a portable library and tutor.