| 1 month | Raises head from prone position | Visually fixes, follows to midline, has tight grasp | Alerts to sound | Regards face |
| 2 months | Holds head in midline, lifts chest off table | No longer clenches fists tightly, follows object past midline | Smiles socially (after being stroked or talked to) | Recognizes parent |
| 3 months | Supports on forearms in prone position, holds head up steadily | Holds hands open at rest, follows in circular fashion, responds to visual threat | Coos (produces long vowel sounds in musical fashion) | Reaches for familiar people or objects, anticipates feeding |
| 4 months | Rolls over, supports on wrists, shifts weight | Reaches with arms in unison, brings hands to midline | Laughs, orients to voice | Enjoys looking around |
| 6 months | Sits unsupported, puts feet in mouth in supine position | Unilateral reach, uses raking grasp, transfers objects | Babbles, ah-goo, razz, lateral orientation to bell | Recognizes that someone is a stranger |
| 9 months | Pivots when sitting, crawls well, pulls to stand, cruises | Uses immature pincer grasp, probes with forefinger, holds bottle, throws objects | Says “mama, dada” indiscriminately, gestures, waves bye-bye, understands “no” | Starts exploring environment, plays gesture games (e.g., pat-a-cake) |
| 12 months | Walks alone | Uses mature pincer grasp, can make a crayon mark, releases voluntarily | Uses two words other than “mama, dada” or proper nouns, jargoning (runs several unintelligible words together with tone or inflection), one-step command with gesture | Imitates actions, comes when called, cooperates with dressing |
| 15 months | Creeps up stairs, walks backward independently | Scribbles in imitation, builds tower of two blocks in imitation | Uses 4–6 words, follows one-step command without gesture | 15–18 months: uses spoon and cup |
| 18 months | Runs, throws objects from standing without falling | Scribbles spontaneously, builds tower of three blocks, turns two or three pages at a time | Mature jargoning (includes intelligible words), 7–10-word vocabulary, knows five body parts | Copies parent in tasks (sweeping, dusting), plays in company of other children |
| 24 months | Walks up and down steps without help | Imitates stroke with pencil, builds tower of seven blocks, turns pages one at a time, removes shoes, pants, etc. | Uses pronouns (I, you, me) inappropriately, follows two-step commands, 50-word vocabulary, uses two-word sentences | Parallel play |
| 3 years | Can alternate feet going up steps, pedals tricycle | Copies a circle, undresses completely, dresses partially, dries hands if reminded, unbuttons | Uses minimum of 250 words, three-word sentences, uses plurals, knows all pronouns, repeats two digits | Group play, shares toys, takes turns, plays well with others, knows full name, age, gender |
| 4 years | Hops, skips, alternates feet going down steps | Copies a square, buttons clothing, dresses self completely, catches ball | Knows colors, says song or poem from memory, asks questions | Tells “tall tales,” plays cooperatively with a group of children |
| 5 years | Skips alternating feet, jumps over low obstacles | Copies triangle, ties shoes, spreads with knife | Prints first name, asks what a word means | Plays competitive games, abides by rules, likes to help in household tasks |