A number of studies have shown that approximately one-quarter of children in potentially bilingual environments do not become bilingual. This article explores several key factors that influence the likelihood that a child who has access to interactions in two languages will learn them both. The five factors discussed are input, language status, access to literacy, family language use, and community support, including schooling. It is argued that the quantity of input has the greatest effect on whether a minority language will be learned, but language status and attitudes about language also play a role. When families are proactive and provide daily activities for children in the minority language, the children respond by learning it. In addition, dual-immersion, "two-way" schooling is shown to benefit children's level of language proficiency in the minority language without diminishing their progress in the community language.