| Motor Skills | Average Age Achieved | Age Range in which 90% Of Infants Achieve the Skill |
| When held upright, holds head erect and steady | 6 weeks | 3 weeks – 4 months |
| When prone, lifts self by arms | 2 months | 3 weeks – 4 months |
| Rolls from side to back | 2 months | 3 weeks – 5 months |
| Grasps Cube | 3 months, 3 weeks | 2 – 7 months |
| Rolls from back to side | 4 months, 2 weeks | 2 – 7 months |
| Sits alone | 7 months | 5 – 9 months |
| Crawls | 7 months | 5 – 11 months |
| Pulls to standing | 8 months | 5 – 12 months |
| Plays patty-cake | 9 months, 3 weeks | 7 – 15 months |
| Stands alone | 11 months | 9 – 16 months |
| Walks alone | 11 months, 3 weeks | 9 – 17 months |
| Builds tower of 2 cubes | 11 months, 3 weeks | 10 – 19 months |
| Scribbles vigorously | 14 months | 10 – 21 months |
| Walks up stairs with help | 16 months | 12 – 23 months |
| Jumps in place | 23 months, 2 weeks | 17 – 30 months |
| Walks on tiptoe | 25 months | 16 – 30 months |
| Voluntary Reaching | ||
| Pre-reaching – batting at objects | 2 months | 1 – 4 months |
| Reaching with ulnar grasp (palm w/ fingers) | 3 months, 3 weeks | 3 – 4 months |
| Transferring object from hand to hand | 4 months | 4 – 5 months |
| Pincer grasp (thumb and finger) | 9 months | 9 – 12 months |
Sources: Bayley, 1993. Berk, 2005