At the beginning of this year, most babies can say only one or two words. "But they understand dozens more," says Andrew Meltzoff, Ph.D., head of the developmental psychology program at the University of Washington in Seattle and coauthor of The Scientist in the Crib (William Morrow, 1999). If you ask your child for his teddy bear, for example, chances are he'll hand it to you, even if he isn't able to say the words.
As the year progresses, children begin to use "protowords" -- made- up words that link sound to meaning. For example, at 18 months, my daughter Zoe said "nummies" whenever she wanted food and "go cah" to go outside.
But the most remarkable part of language development is what experts call the "naming explosion," which typically occurs between 18 and 21 months. "Seemingly overnight, a child goes from knowing a few words to labeling everything in sight," says Dr. Ramey. "Some children learn as many as 50 new words a week." By the time your child is 2, he'll be able to ask and answer questions, speak in simple sentences, say "please" and "thank you," and name as many as 350 objects.