One of the things CDE (and, for that matter, No Child Left Behind) is trying to do is reduce the difference in how well different racial or ethnic groups do on achievement tests in K-12. Researchers are tracing back when the difference begins.
A recent study out of Berkley by Bruce Fuller and others says that, for children of poor immigrant Latinas, it starts around one year of age. Nine to 15-month old white and Latino kids are about the same, but by 2 or 3, the Latino kids are up to 6 months behind in things like vocabulary, speaking in complex sentences, and doing puzzles. That's an extremely fast drop, or more likely a failure to participate in other kids' extremely fast development.
In general they attribute the difference to lower average maternal education, which explains lots of stuff. Poor Latinas read to their kids less and tell fewer stories, so their kids know fewer words and have been introduced to fewer concepts.
Looks to me like strong evidence for expanding Early Head Start and having State Preschool start at age 1.
LA Times summary article.