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Childhood Development


Evan G. Graber

, DO, Sydney Kimmel Medical College

Last full review/revision Apr 2021| Content last modified Apr 2021

Between the ages of 1 and 13, children's physical, intellectual, and emotional capabilities expand tremendously. Children progress from barely tottering to running, jumping, and playing organized sports. At age 1, most children can utter only a few recognizable words. By age 10, most children can write book reports and use computers. However, the rate of intellectual, emotional, and behavioral development varies considerably from infant to infant and from child to child. Development depends in part on

  • Heredity: Certain patterns may run in families, such as late walking or talking.
  • Nutrition: Proper nutrition is essential to development.
  • Environment: For example, lack of sufficient mental stimulation can slow development, whereas appropriate stimulation can speed development.
  • Physical problems in the child: For example, deafness can slow language development.

(See also Learning and Developmental Disorders.)

Although a child's development is usually continuous, temporary pauses may occur in the development of a particular function, such as speech. Doctors use established milestones—the age when most children master certain skills such as walking—to determine how a child is developing compared with other children. Various skills can develop at different rates. For example, a child may walk late but speak in sentences early.

Developmental Milestones From Birth to Age 12 Months*




  • Sleeps much of the time
  • Sucks
  • Cries in response to discomfort and disturbances

4 weeks

  • Brings hands toward eyes and mouth
  • Moves head from side to side when lying on stomach
  • Follows a moving object that is in front of the face
  • Responds to a noise in some way, such as startling, crying, or quieting
  • May turn toward familiar sounds and voices
  • Focuses on a face

6 weeks

  • Regards objects in the line of vision
  • Begins to smile when spoken to
  • Lies flat on stomach

3 months

  • Holds head steady when sitting
  • Raises head 45 degrees when lying on stomach
  • Opens and shuts hands
  • Pushes down when feet are placed on a flat surface
  • Swings at and reaches for dangling toys
  • Follows an object that is in front of the face from one side to the other
  • Watches faces intently
  • Smiles at sound of caretaker's voice
  • Begins to make speechlike sounds

5–6 months

  • Holds head steady when upright
  • Sits with support
  • Rolls over one way, usually from stomach to back
  • Reaches for objects
  • Recognizes people at a distance
  • Listens intently to human voices
  • Smiles spontaneously
  • Squeals in delight
  • Babbles to toys

7 months

  • Sits without support
  • Bears some weight on legs when held upright
  • Transfers objects from hand to hand
  • Holds own bottle
  • Looks for dropped object
  • Responds to own name
  • Responds to being told “no”
  • Babbles, combining vowels and consonants
  • Wiggles with excitement in anticipation of playing
  • Plays peekaboo

9 months

  • Sits well
  • Works to get a toy that is out of reach and objects if toy is taken away
  • Crawls or creeps on hands and knees
  • Pulls self up to standing position
  • Gets into a sitting position from stomach
  • Stands holding on to someone or something
  • Says “mama” or “dada” indiscriminately

12 months

  • Walks by holding furniture ("cruising") or others' hands
  • May walk one or two steps without support
  • Stands for a few moments at a time
  • Says "dada" and "mama" to the appropriate person
  • Drinks from a cup
  • Claps hands and waves bye-bye
  • Speaks several words

* The age at which children meet milestones varies greatly. The age ranges here represent the average age.

Developmental Milestones From Ages 18 Months to 6 Years*


Gross Motor Skills

Fine Motor Skills

18 months

  • Walks well
  • Can climb stairs holding on
  • Draws vertical stroke
  • Makes a tower of 4 cubes
  • Turns several book pages at a time
  • Speaks about 10 words
  • Pulls toys on strings
  • Partially feeds self

2 years

  • Runs well/with coordination
  • Climbs on furniture
  • Handles a spoon well
  • Turns single book pages
  • Makes a tower of 7 cubes
  • Makes 2- or 3-word sentences

2½ years

  • Jumps
  • Walks upstairs and downstairs without help
  • Scribbles in a circular pattern
  • Opens doors
  • Puts on simple clothing
  • Speaks regarding toilet needs

3 years

  • Mature gait in walking
  • Rides tricycle
  • Favors using one hand over the other
  • Copies a circle
  • Dresses well except for buttons and laces
  • Counts to 10 and uses plurals
  • Recognizes at least 3 colors
  • Asks questions constantly
  • Feeds self well
  • About half of children can take care of toilet needs

4 years

  • Walks up and down stairs, alternating feet
  • Hops on one foot
  • Throws a ball overhand
  • Copies a cross
  • Dresses self
  • Washes hands and face

5 years

  • Skips
  • Catches a bounced ball
  • Copies a triangle
  • Draws a person in 6 parts
  • Knows 4 colors
  • Dresses and undresses without help

6 years

Walks along a straight line from heel to toe

Writes name

* The age at which children meet milestones varies greatly. The age ranges here represent the average age.

Intellectual Development

Intellect is a person's capacity for understanding, thinking, and reasoning. For intellect to develop, children must receive proper nurturing in infancy and early childhood. For example, reading to children from an early age, providing intellectually stimulating experiences, and providing warm and nurturing relationships all have a major impact on their intellectual growth and development.

At the age of 2, most children understand the concept of time in broad terms. Many 2- and 3-year-old children believe that anything that happened in the past happened "yesterday," and anything that will happen in the future will happen "tomorrow." A child at this age has a vivid imagination but has difficulty distinguishing fantasy from reality. By age 4, most children have a more complicated understanding of time. They realize that the day is divided into morning, afternoon, and night. They can even appreciate the change in seasons.

From 18 months to 5 years of age, a child's vocabulary quickly expands from about 50 words to several thousand words. Children can begin to name and to actively ask about objects and events. By age 2, they begin to put two words together in short phrases, progressing to simple sentences by age 3. Pronunciation improves, with speech being half-understandable to a stranger by age 2 and fully understandable by age 4. A 4-year-old child can tell simple stories and can engage in conversation with adults or other children.

Even before 18 months of age, children can listen to and understand a story being read to them. By age 5, children are able to recite the alphabet and to recognize simple words in print. These skills are all fundamental to learning how to read simple words, phrases, and sentences. Depending on exposure to books and natural abilities, most children begin to read by age 6 or 7.

By age 7, children's intellectual capabilities become more complex. By this time, children become increasingly able to focus on more than one aspect of an event or situation at the same time. For example, school-aged children can appreciate that a tall, slender container can hold the same amount of water as a short, broad one. They can appreciate that medicine can taste bad but can make them feel better, or that their mother can be angry at them but can still love them. Children are increasingly able to understand another person's perspective and so learn the essentials of taking turns in games or conversations. In addition, school-aged children are able to follow agreed-upon rules of games. Children of this age are also increasingly able to reason using the powers of observation and multiple points of view.

Emotional and Behavioral Development

Emotion and behavior are based on the child's developmental stage and temperament. Every child has an individual temperament, or mood. Some children may be cheerful and adaptable and easily develop regular routines of sleeping, waking, eating, and other daily activities. These children tend to respond positively to new situations. Other children are not very adaptable and may have great irregularities in their routine. These children tend to respond negatively to new situations. Still other children are in between these two ends of the spectrum.


Crying is an infant's primary means of communication. Infants cry because they are hungry, uncomfortable, distressed, and for many other reasons that may not be obvious. Infants cry most—typically 3 hours a day—at 6 weeks of age, usually decreasing to an hour a day by 3 months of age. Parents typically offer crying infants food, change their diaper, and look for a source of pain or discomfort. If this does not work, holding or walking with the infant sometimes helps. Occasionally nothing works. Parents should not force food on crying infants, who will readily eat if hunger is the cause of their distress.

At about 8 months of age, infants normally become more anxious about being separated from their parents. Separations at bedtime and at places like child care centers may be difficult and can be marked by temper tantrums. This behavior can last for many months. For many older children, a special blanket or stuffed animal serves at this time as a transitional object that acts as a symbol for the absent parent.


At 2 to 3 years of age, children begin to test their limits and do what they have been forbidden to do, simply to see what will happen. The frequent "nos" that children hear from parents reflect the struggle for independence at this age. Although distressing to parents and children, tantrums are normal because they help children express their frustration during a time when they cannot verbalize their feelings well. Parents can help decrease the number of tantrums by not letting their children become overtired or unduly frustrated and by knowing their children's behavior patterns and avoiding situations that are likely to induce tantrums. Rarely, temper tantrums need to be evaluated by a doctor. Some young children have particular difficulty controlling their impulses and need their parents to set stricter limits around which there can be some safety and regularity in their world.

At age 18 months to 2 years, children typically begin to establish gender identity. During the preschool years, children also acquire a notion of gender role, of what boys and girls typically do. Exploration of the genitals is expected at this age and signals that children are beginning to make a connection between gender and body image.

Between 2 and 3 years of age, children begin to play more interactively with other children. Although they may still be possessive about toys, they may begin to share and even take turns in play. Asserting ownership of toys by saying, "That is mine!" helps establish the sense of self. Although children at this age strive for independence, they still need their parents nearby for security and support. For example, they may walk away from their parents when they feel curious only to later hide behind their parents when they are fearful.

At 3 to 5 years of age, many children become interested in fantasy play and imaginary friends. Fantasy play allows children to safely act out different roles and strong feelings in acceptable ways. Fantasy play also helps children grow socially. They learn to resolve conflicts with parents or other children in ways that help them vent frustrations and maintain self-esteem. Also at this time, typical childhood fears like that of "the monster in the closet" emerge. These fears are normal.

At 7 to 12 years of age, children work through numerous issues: self-concept, the foundation for which is laid by competency in the classroom; relationships with peers, which are determined by the ability to socialize and fit in well; and family relationships, which are determined in part by the approval children gain from parents and siblings. Although many children seem to place a high value on the peer group, they still look primarily to parents for support and guidance. Siblings can serve as role models and as valuable supports and critics regarding what can and cannot be done. This period of time is very active for children, who engage in many activities and are eager to explore new activities. At this age, children are eager learners and often respond well to advice about safety, healthy lifestyles, and avoidance of high-risk behaviors.

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