In this column Manyak and Bauer summarize key research addressing the English vocabulary development of English learners (ELs) and distill implications for instructional practice. First, the authors discuss several key studies that demonstrate the limitation of many ELs' English vocabulary knowledge and the negative impact of this limitation on ELs' reading comprehension. Next, they present details of recent studies focused on vocabulary instruction for ELs, highlighting findings that ELs benefit from well-designed instruction of specific words and word learning strategies. Finally, the authors present six important practical guidelines for designing and implementing rich vocabulary instruction for ELs.