Yet half of all kids get to kindergarten without the skills they need - like reading.
A program works through pediatricians to help more children get on track.
At just 2 years of age, little amelia is already hooked on books.
"Doggie - woof, woof, woof," she says as she points at her Animals book.
Her mom, Meaghan Alfarano, started reading to her before she was born.
"Because her dad was on the road. I would just read to her to keep myself company," says Alfarano.
Amelia's interest took off with her first book through Reach Out & Read.
"It was Llama Llama Hippity Hop, and it is still one of Amelia's favorite books," she says with a smile.
At each routine checkup from 6 months to 5 years, pediatricians give kids a new book.
Dr. Gabriela Marein-Efron of Children's Hospital says starting early, with infants, is a must.
"People say to me - read to babies? They don't understand the words."
"Even though it may not seem like the child is listening, they really are," says Dr. Marein-Efron.
"If kids are not read to, it makes it much harder for them to develop those critical thinking skills, and successful school skills later on," she adds.
All the books are geared toward a child's age, and many Children's Hospital primary care centers have dual-language books, depending on a neighborhood's ethnic mix -
Gently used books donated by the public are also in waiting rooms and offices, for reading during other visits.
Dr. Marein-Efron says a child's earliest books should be sturdy ones they can handle and explore -
And then come ones with everyday objects to identify.
"Can you count the chicks for me?" says Meaghan.
Without missing a beat, Amelia counted without hesitation, "1, 2, 3, 4, 5."
Parents Meaghan and Tito say she can go all the way to 10.
Dr. Marein-Efron says there's no magic amount of time, or time of day for reading out loud.
"Just do it as often as you can, as long as you can," she says.
Amelia's skill with colors, numbers, and words amazes her parents.
"She's amazing. She's like a little sponge," says her proud mother.
Children's Hospital gives out 55-thousand new books every year, and uses 200-thousand gently used books in its offices.
For a list of new books they accept in donation, or for information on donating gently-used books to their Reach Out and Read effort, click here.
WATCH: Dr. Marein-Efron habla con familias de habla hispana sobre la importancia de leer libros para bebés y niños pequeños.
(Dr. Marein-Efron talks to Spanish-speaking families about the importance of reading to babies and toddlers.)