Two-year-old children with larger oral vocabularies enter U.S. kindergarten classrooms better at reading and mathematics as well as better behaved, according to a team of researchers lead by Paul Morgan, associate professor of education policy studies, Penn State.

Other research has found that children who are doing better academically in kindergarten are more likely to go to college, get married, own homes and live in higher-income households.

"Our findings provide compelling evidence for oral vocabulary's theorized importance as a multifaceted contributor to children's early development," Morgan said.

Morgan, who worked with researchers at Penn State, the University of California, Irvine, and Columbia University, examined data from parental surveys reporting on the size of their children's vocabularies at two years of age. The researchers found that vocabulary gaps between groups of U.S. children were already evident by this early time period. Females, those from more economically advantaged families, and those receiving higher quality parenting had larger oral vocabularies. Children born with low birth weight or who were being raised by mothers with health problems had smaller vocabularies.

When Morgan and his colleagues looked at how the children were doing three years later in kindergarten, they found that children with larger vocabularies at two years of age were better readers, knew more about mathematics, were more attentive and task persistent, and were less likely to engage in acting out- or anxious-type behaviors. This was the case even after adjusting for the family's economic resources, the children's prior cognitive functioning and behavior, and many other factors.

The research appears in the latest edition of Child Development and supports prior studies showing that vocabulary differences emerge very early during children's development and help to explain later differences in how children are doing in school. The study's findings underscore the importance of early intervention.

"Our findings are also consistent with prior work suggesting that parents who are stressed, overburdened, less engaged and who experience less social support may talk, read, or otherwise interact with their children less frequently, resulting in their children acquiring smaller oral vocabularies," Morgan explained.

"Interventions may need to be targeted to two-year-olds being raised in disadvantaged home environments," Morgan's colleague George Farkas, professor of education at the University of California, Irvine, said, adding that home visitation programs that provide assistance to disadvantaged, first-time mothers before and after childbirth may help clarify the role parents play by connecting them to various social services and support systems.

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Penn State colleagues Marianna Hillemeier, professor of health policy and administration and demography and Steve Maczuga, research programmer and analyst for Penn State's Population Research Institute, as well as Carol Scheffner Hammer, professor of communication science at Columbia University, also contributed to this research.

The National Center for Special Education Research, Institute of Education Sciences, U.S. Department of Education, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institutes of Health supported this work.