zaslow_1598571613_ch11_257-280 2/3/11 4:28 PM Page 257 CHAPTER 11 Defining and Measuring Quality in Early Childhood Practices that Promote Dual Language Learners’ Development and Learning Dina C. Castro, Linda M. Espinosa, and Mariela M. Páez T he number of young dual language learners (DLLs) 1 enrolling in early childhood programs has increased steadily over the last 15 years, a trend that is expected to continue. A factor contributing to this trend is the rapid growth of the immigrant population. As of 2005, one in four, or 25%, of young children in the United States were children of immigrant families (Hernandez, Denton, & Macartney, 2008). Although a large percentage (62%) of children in immigrant families live in five states (California, Florida, Illinois, New York, and Texas), their percentages have increased in most of the other states, with children of immigrants accounting for at least 10% of children in 26 states (Hernandez et al., 2008). There is enormous diversity in the origin of immigrant families. Among immigrant parents of children under 6 years of age, the largest percent age come from Mexico and other Latin American countries and the Caribbean (64%), and smaller percentages come from countries in Asia (23%), Europe and Canada (7%), and Africa and the Middle East (6%) (Capps et al., 2005). The majority of children in immigrant families grow up in bilingual environments. Data from the U.S. Census Bureau indicate that 84% of immigrants ages 5 and older speak a language other than English at home (Pew Hispanic Center, 2009). The linguistic diver sity among young children is evident in the increase of young DLLs’ enrollment in Head Start programs, over 30% nationally; almost 85% of those children are from families who speak Spanish as their primary language (Office of Head Start, 2007). The percentage of DLLs is larger among the youngest children in the public education system. In 2000–2001, the average percentage of DLLs in prekindergarten (pre-K) through grade 12 education was 10%; however, 44% of all DLLs were enrolled in pre-K to third grade (Kindler, 2002). 257