The 30 Million Word Difference

For decades, education researchers have found that children from lower-income and less-educated parents typically enter kindergarten with limited language skills compared to their more privileged peers. Results from Stanford University psychologist Dr. Anne Fernald’s latest study suggest these socioeconomic status (SES) differences emerge even earlier than previously understood. By 18 months, toddlers from more affluent households (who come from communities where the median income per capita is $69,000) have significantly better and faster language processing skills than low-income children (who come from communities with a median income per capita of $23,900).

Fernarld’s research reinforces previous findings that show professional parents speak much more to their children, with high-SES children hearing roughly 30 million more words by age three than children from low-SES households. Because vocabulary and oral language development are connected to reading comprehension, these school readiness differences have long-term consequences. For example, Dr. David Dickinson (Vanderbilt University) and Dr. Catherine Snow (Harvard University) tracked students from age three through middle school and found a child’s vocabulary test score in kindergarten could predict reading comprehension in later years.

Such research provides a compelling argument for policy makers to increase access to high-quality childcare and investment in programs for children birth through kindergarten, particularly for low-income families. Others argue that so few programs offer high-quality instruction, expanding early childhood instruction could prove to be a waste of money and turn their focus on parents. However, Dickinson cautions that vocabulary flashcards and rote memorization do not replace natural conversations with children. For example, literacy experts emphasize the need to ask questions while reading books and helping children expand their word familiarity during playtime.

In Fernald’s previous work on Spanish-learning children, she found large differences in levels of parental engagement within a group of economically disadvantaged families. Even low-SES kids who heard more child-directed talk learned language more rapidly. “It’s clear that SES is not destiny,” Fernald said. “The good news is that regardless of economic circumstances, parents who use more and richer language with their infants can help their child to learn more quickly.”


Build math confidence

Lots of kids dread math. You can help them love it. Get advice on how from our Teach. Learn. Grow. math experts in our latest ebook.


Blog post

For policymakers

There’s a lot policymakers can do to support schools during COVID-19. We talked with experts Evan Stone and LaTanya Pattillo about what to focus on during SY21–22.

Read the post


The ABCs of reading

Effective literacy instruction must rely on the science of reading and best practices in balanced literacy.

Learn more


Sign up for our newsletter and get recent blog posts—and more—delivered right to your inbox.