Below are a series of ages and stages charts that describe developmentally appropriate behavior and causes for concern for various ages.

“There are sensitive periods for developing certain abilities (such as when infants form attachments with their parents) that, if unachieved, could impair later development. Every child grows at his or her own pace, but most children achieve developmental milestones within the same general timeline. Keep in mind that the impact of abuse or neglect may cause children to develop at a slower rate (Perry, 2006) and that children born prematurely may also achieve milestones at different times, depending on the degree of prematurity. The chart [in this publication] provides general guidance on developmentally appropriate behavior in children, behaviors of the child or parent that may be a cause for concern, and positive parenting strategies. You may want to adjust your expectations according to the child’s needs and the parent’s situation.“

Ages and Stages chart 1, ages 0-7 months
Ages and Stages chart 2, ages 8-24 months
Ages and Stages chart 3, ages 3-4 years
Ages and Stages chart 4, ages 5-7 years
Ages and Stages chart 5, ages 8-14 years
Ages and Stages chart 6, ages 15-18 years

Source: Supporting Brain Development in Traumatized Children and Youth
U.S. Department of Health and Human Services, Administration for Children and Families, Child Welfare Information Gateway, August 2011.
https://www.childwelfare.gov/pubs/braindevtrauma.pdf#page=5&view=Ages