What are the child development milestones?

From birth through age 5, physical milestones are easy to monitor. Simply watch your child to see whether she performs the behavior.

At 1 month old, an infant is typically doing more than sleeping, eating and requesting a diaper change. She jerks her arms and waves her hands near her mouth. Position her prone for some "tummy time," and she'll turn her head to either side.

Jump ahead to 3 months, and tummy time is generally livelier. She should be lifting her head and chest from the bed and be using her arms to prop herself up. Her lower body should be kicking and stretching. A child's awareness of the world is growing at this age, so she should be able to bring her hand to her mouth and track movement with her eyes. And, finally, the much-anticipated parental payoff: a social smile in response to a familiar voice.

The next milestone is marked at 6 months, about the time her first tooth should erupt. At 7 months, she should be able to roll from stomach to back and from back to stomach. She may sit up alone, perhaps bracing herself with her hands. Fine motor skills also improve: She should be able to claw an object toward her, and when she's holding the item, she may trade hands.

By the end of the first year, she's likely Miss Independence, actively crawling and "cruising" (walking by holding onto furniture). She should be able to pull herself into a standing position and balance unaided, briefly. At mealtime, she may be using the pincer grasp (thumb and index finger) to feed herself small bits and, with assistance, drink from a cup.

Skipping ahead to 2 years, she should walk alone and run in an enthusiastic, if ungainly, manner. At 3, she should be climbing and descending stairs competently. By 4, she should be able to balance on one foot and dress herself.

During middle childhood (ages 6 to 8), the Tooth Fairy stops by as baby teeth begin to fall out and are replaced by permanent teeth. A growth spurt should hit her in later childhood (ages 9 to 11), though her male classmates likely won't start theirs until early adolescence (ages 12 to 14). Around this time is the arrival of menarche (her first menstrual period). Both males and females develop an increased need for sleep, although, because of school schedules and growing independence, it's very likely they won't get enough rest.

You may ask: What's happening internally as we see all these external changes? That's where we're heading next -- cognitive development.

It can be difficult to observe and measure an infant's cognitive development until he's about 3 months old, when he should begin responding to bright colors, lights, noisy rattles and human voices by turning toward them. Meal times highlight the daily agenda: He recognizes the breast or bottle and eagerly responds.

During the first 12 months, he's exploring. By the end of that time, he should have discovered several ways to investigate items, such as shaking, rolling, banging and throwing. (By now, you've probably learned to put all breakable items out of his reach.) These investigations should lead to preliminary competence, during which he starts to correctly use objects, such as a brush, a cup or a toy phone.

Around 2 years old, he should begin imaginative play and "make believe." Much of this play involves social situations. By 3, he should be aware that he and others think (also known as the theory of mind) [source: Price]. Jump to age 4, and he should have learned to count at least ten blocks, raisins or pennies. He should have a concept of time by age 5 (but that doesn't necessarily mean he'll hurry up or get ready quickly).

From about ages 6 to 8, he should be able to talk meaningfully about his feelings and ideas. (He may hold a real conversation about his favorite movie or explain why it's lousy that he got picked last for kickball.) Reading and mathematical skills tend to develop dramatically at this age. He also should be less egocentric. That doesn't necessarily mean he's been selfish, but just that he's literally more aware of others now.

More great cognitive leaps are pending:

That's what'll likely be going on inside his head for the first seventeen years. What will all this thinking prompt him to say? Up next, we'll take a look at language development.

Language milestones involve more than the number of words a child can speak. It's also about comprehending speech and using and understanding facial expressions and body language. Communication begins very early.

At 3 months, your child should be giggling and cooing. As mentioned earlier, she also may be smiling at familiar voices. That's cognitive development, certainly, but it's connected to language as well. She communicates what she has learned: Someone she likes is around.

By the time she is 7 months old, she should respond to her name and may start to acknowledge "no." (Then again, just because she understands, "No, don't eat the cookie," doesn't necessarily mean she won't do it anyway.) She will probably babble syllables in strings rather than as isolated sounds. But the babbling should be expressive -- you'll know whether she's happy or sad.

At 1 year old, parents will experience another delight: She should begin regularly calling to them, generally with the common terms "mama" and "dada." On the other hand, she'll probably use gestures for "no," such as an emphatic headshake signifying, "No, I don't want those mushy peas!"

In another year, she should be able to verbalize at least 50 words, and parents will usually understand at least half of them. She may put two words together, often to make her desires known: "Daddy, up!" or "No bed!"

By 3 years of age, she should be able to label ordinary objects and state her own name and age. At 4, she should know how to tell simple stories, and even strangers should be able to understand her speech. The following year, she should be able to articulate her full name and address.

Beyond early childhood, it's primarily a matter of more and better:

From the first coo to a book report on "War and Peace," language development is fast and furious. Much of that language expression and reception takes place in social settings, so let's check out social and emotional developmental milestones next.

Social and emotional development is an area of concern for most parents, who want their children to grow up feeling happy, secure and connected. Milestones are first identified at 3 months, when infants provide feedback to parents on feelings and relationships. As mentioned previously, the social smile emerges. Not only is he physically capable of manipulating facial muscles to form a smile, but he also uses it to indicate pleasure at your company. He delights in playful interactions with others, even that old standby, "peek-a-boo." Play also extends to imitation, often comical mugging or gestures.

Seven months brings an awareness of others' emotions. He should react to a look on your face. So, if you show an angry response to a political report on the radio, for example, he might start whimpering at your scowl.

By the end of the first year, he should have developed strong loving bonds with his parents (or the primary caregiver, if that's another person). This attachment has positive and negative aspects. On the up side, he'll prefer you and seek you out above others. On the down side, he'll prefer you and seek you out above all others. This behavior is often known as stranger anxiety, or the fear of unknown adults, which can vary from shyness when meeting new people to hysterics when you leave, depending on the child [source: Berk]. Thankfully, after two years, temporary separation from his parents should no longer produce major disruptions. By age 3, partings should be amicable because he understands you'll return.

Five years of age should bring an understanding of rules (though not the certainty that he'll choose to follow them). He should comprehend the basic physical differences between males and females and accept their constancy. A desire for independence should also emerge, which sets the stage for future social and emotional milestones, such as the following:

Although social and emotional, physical, cognitive and language milestones are generally considered universal, there are some cultural differences. The next section takes us on an international tour of milestones.

Cultural differences in milestones have been observed in all developmental areas.

Once 3-year-olds develop a theory of mind (the realization that people think), then this cognitive ability can be combined with language and social skills. One result: Children begin to lie. They understand rules, actions and outcomes, and they may lie to avoid punishment. But there are other reasons they might lie, and it might differ from culture to culture.

For example, one study compared the differences between North American and Chinese children. The North American children indicated they would lie to their coach to protect a teammate who was missing a game to study, even if the team was adversely affected. This could show that, in this society, the individual is highly valued. The study also found that the Chinese children would not lie under those circumstances but would lie if it benefited the team. This may reflect an emphasis on group accountability in Chinese culture [source: Price].

Although a developmental advancement, lying is not generally admired by most parents. Milestones can be distressing, such as stranger anxiety. But could there be an advantage to a strong fear of outsiders? In some parts of the world, adults perceive the presence of any stranger as a potential threat. Living on a secluded Israeli kibbutz, for example, may increase its members' chances of being targeted by terrorists. Adults there can be suspicious of any unknown persons, and, sensing this, their babies may have a dramatically higher level of stranger anxiety [source: Berk].

Children often rely on adult guidance, and this can be reflected by differences in toddlers' language development. A 2-year-old in an English language society will verbalize at least 50 words, but they will be nouns, primarily, because that's what she's hearing from her caregivers: "Here's your bottle," "See the doggie," "Mommy's home!" In contrast, Chinese and Korean youngsters hear more verbs and social phrases from their mothers, so toddlers are reproducing that kind of language [source: Berk].

Language and social development rely on personal interactions, so it's unsurprising that there are cultural differences, because people connect differently depending on where they are from. Physical milestones can also be affected as parents respond to cultural norms.

For example, many Western societies promote putting infants to sleep on their backs to prevent SIDS (Sudden Infant Death Syndrome). These babies may spend comparatively less time on their stomachs and be slower to roll over, crawl and sit up. To counter this, parents are often encouraged to place infants on their stomach during waking hours ("tummy time").

In Mexico, the Zinacanteco people of Mexico delay physical development of their babies because of safety concerns. Toddlers' unrestricted running and walking can be hazardous because they lack the cognitive awareness that will keep them away from open fires.

In Jamaica, many parents encourage some accelerated physical development. By placing babies waist-deep in holes in the ground and supporting the infants' posture with blankets, the parents hasten independent sitting skills [source: Berk].

Monitoring milestones is worldwide, even if there are cultural variations. However, some specialists prefer using other methods to track children's development, as we discover in the next section.

Not all child development professionals consider milestones to be accurate measures. Many developmental psychologists, the researchers who study childhood transformation, avoid all but the motor milestones, which are generally accepted because they are less complicated and display less variance among children. Yet even physical development is not consistent: Some children may skip steps (never learning to crawl, for example), and some may exhibit a behavior once and don't repeat it consistently. A baby may roll over once, surprising herself and her parents, then not repeat it for weeks.

Grant Gutheil, a developmental psychologist at Nazareth College in Rochester, N.Y., offered an analogy to make some sense of milestones: "Milestones in child development can be seen like a car with square wheels. Each turn of the wheel is a new stage. There's a lot of struggle and waiting until the wheels turn…thunk! And, suddenly, you're in the new stage."

Child development in general is more continuous and variable, however. The car actually has round wheels; it goes forward and backward and may go down a blind alley. Occasionally, there's a flat tire.

According to Gutheil, there are many aspects of development that parents mistakenly assume have a linear progression, such as sharing, self-awareness and academic ability. Say, for instance, that your child won't share and is reluctant to loan her doll to her playmate or her books to her siblings. Then one day, she offers her teddy bear to a friend, and the parents celebrate. The next week, however, she smacks her younger brother for playing with her blocks. It's as if she never had the breakthrough, but that pattern can be very common in a child's development. She might try something new, experiment with it a bit, stray, and return until she's consistently exhibiting that behavior.

Child development is multi-dimensional as well, meaning that development in one area is often connected to another. Is that social smile an indication of cognitive, social or language development -- or all three? If it is all three, should they really be separate milestones?

Because many developmental psychologists ordinarily don't use milestones, they use other methods to discuss changes in development. Some options include the following:

Whether or not you find the concept of milestones useful, child development is a process. Changes will occur, although not always at a pace parents might prefer.

Read on to learn more about milestones, child development and related topics.