Quite often, educators tell families of children who are learning English as a second language to speak only English, and not their native language, at home. Although these educators may have good intentions, the authors argue that the educators' advice to families is misguided and stems from misunderstandings about the nature of bilingualism and the process of language acquisition. This misguided advice that students should speak only English is given primarily to poor families with limited educational opportunities, because children from poor families often are identified as at-risk for academic failure, not to wealthier families who have many educational advantages. Here, the authors discuss the personal, cognitive, social, and economic advantages of bilingualism and suggest that, instead of telling families to stop using their native languages and speak only English, educators should offer myriad opportunities for language and cognitive development in both languages.