The growth in English Learner (EL) students in U.S. public schools continues to be unprecedented, with the majority of the change taking place in communities with little or no experience educating children not fluent in English. It is estimated that by 2030, ELs will comprise 40% of the school population (Maxwell & Shah, 2011). As a group, ELs are diverse and represent over 322 languages nationwide (Ballantyne, Sanderman, & Levy, 2008). The largest linguistic subgroup among all ELs (85%) speaks Spanish as their native language. The next most common native languages, in order, are Chinese (includes Mandarin and Cantonese), Vietnamese, Hmong, and Korean (Ballantyne et al., 2008). Due to the linguistic and cultural diversity within their homes, EL students often lack access to Standard English models and thereby face challenges learning in this setting. Consequently, ELs' academic achievement often trails behind children from English-only homes. The growth of ELs nationally and their historic underachievement has created significant interest in strategies and instruction that have demonstrated effectiveness in promoting greater academic success. This chapter provides a discussion of the factors that influence the academic development of ELs and offers guidance on how to deliver instruction and use strategies that promote the academic success of all ELs.