Children between the ages of zero and eight years old are the most diverse age group in the United States. Compared to other age groups, they are more likely to be racial and/or ethnic minorities, be born to immigrant parents, and speak a language other than English. Many of these young children are considered dual language learners (DLLs). Yet despite this fact, it is difficult to find a good estimation for just how many DLLs there are. At the early childhood education level, Head Start, Early Head Start, and some state-funded preschool programs keep track of DLLs, but these data are incomplete at best.

School and census data both provide estimates of English language learners (ELLs) and immigrant children, respectively, but neither of these equate to DLLs. The number of ELLs refers to all school-age children (for the difference between DLLs and ELLs, click here), and does not account for the large number of DLLs between the ages of zero to four years old. And while Head Start does track DLLs, the program is not compulsory and therefore does not include all preschool age children. Moreover, data from the Center on Enhancing Early Learning Outcomes (CEELO) and the National Institute for Early Education Research (NIEER) indicate that only 22 states report the number of DLLs enrolled in their pre-kindergarten programs. Data on DLLs enrolled in early childhood programs is hard to come by because the majority of states do not require language screening and assessments.

At the elementary level, some DLLs may not be officially designated as ELLs if they do not test into ESL services or if their parents refuse this label. Likewise, U.S. Census data provides estimates of numbers of children born to immigrant parents, but this does not include children who may be third- or fourth-generation immigrants and grow up in a home where a language other than English is spoken. This figure also includes children of immigrants who live in households where English is the primary language (or families report it as such) and therefore would also not be considered DLLs.

Based upon 2015 Census data projections for children under eight, children with foreign born parents, and percentage of the population that speaks a language other than English, a reasonable estimate for the number of DLLs is somewhere between seven and nine million, or between 21-27 percent of children under the age of eight. This estimate is nearly double the most recent count of all K-12 ELLs (4.85 million or 10 percent of all students in the 2012-2013 school year).

While we don’t currently know the exact number of DLLs, we do know that there is substantial diversity in their ethnicities, linguistic backgrounds, and home environments. The majority of DLLs are U.S. citizens - over 75 percent of elementary ELL students and 75 percent of LEP students between the ages of 5 and 18 are native born U.S. citizens. Overall, 40 percent of immigrant families in the U.S. come from Mexico, but the remaining 60 percent come from all over the globe—including the Caribbean (7 percent), Latin America (13 percent), and Asia (19 percent). While DLLs speak some 150 languages, the majority of them are Spanish speakers. In fact, about 73 percent of ELLs speak Spanish, but since only 64 percent of 4 year-old Hispanic children are enrolled in public or private preschools, the number of young Spanish-speaking DLLs is harder to calculate.

A 2012 report by NIEER estimates the predominant language spoken by 3 and 4 year-old Hispanic DLLs enrolled in Head Start, public, or private preschools using data from the National Household Education Survey. Nearly 51 percent of these 4-year olds were predominantly Spanish speakers, and over 73 percent spoke Spanish and English at home. Of 3 year-old children enrolled in preschool programs, nearly 27 percent are predominantly Spanish speakers and another 27 percent speak English and Spanish at home.

The next largest language group after Spanish is Chinese, although Chinese speakers constitute less than five percent of DLLs. Overall, however, about a quarter of DLLs speak 149 other languages!

It is commonly noted that DLLs, particularly those that are children of immigrants, are more likely than their monolingual peers to have parents who do not speak English fluently and/or have not yet completed high school. Additionally, DLLs tend to have relatively stable home environments. In fact, most DLLs (about 56 percent) live with at least one parent who is a U.S. citizen and most (about 54 percent) live in family-owned homes. DLLs are also more likely than the general population to live in two-parent households and are also more likely to have other adults, such as grandparents or other relatives, living in their homes.

Historically, DLLs have tended to cluster in cities, and traditional immigrant enclaves (e.g. Los Angeles, New York, Chicago) continue to have the highest concentrations of DLLs. However, new immigrant communities are popping up across the U.S. For instance, the state of South Carolina experienced an 800 percent increase in their ELL subgroup between 1997 and 2008.