Reflexive communication—cries, movements, facial expressions.

A range of meaningful noises—cooing, fussing, crying, laughing.

New sounds, including squeals, growls, croons, trills, vowel sounds.

Babbling, including both consonant and vowel sounds repeated in syllables. Examples: ma-ma-ma, da-da-da, ba-ba-ba.

Comprehension of simple words; speech-like intonations; specific vocalizations that have meaning to those who know the infant well. Deaf babies express their first signs; hearing babies also use specific gestures (e.g., pointing) to communicate.

Slow growth of vocabulary, up to about 50 words. Can learn names of caregivers, siblings, pets, and favorite foods, as well as refer to elimination. Examples: mama, nana; pee-pee, doo-doo.

Naming explosion—three or more words learned per day. Much variation: Some toddlers do not yet speak.

First two-word sentence. Examples: More juice. Baby cry.

Multiword sentences. Half the toddler’s utterances are two or more words long. Example: Mommy read book.