Overview

Children usually progress in a natural, predictable sequence from one developmental milestone to the next. But each child grows and gains skills at their own pace. Some children may be advanced in one area, such as language, but behind in another, such as sensory and motor development.

Milestones usually are grouped into five major categories: physical growth, cognitive development, emotional and social development, language development, and sensory and motor development.

Physical development

Most children by 18 months of age:

• Gain weight and grow at a steady but slower pace than during their first 12 months of life. Between 12 and 24 months of age, expect your child to gain about 1.4 to 2.3 kg (3 to 5 lb), grow an average of 7.6 to 12.7 cm (3 to 5 in.), and gain about 2.5 cm (1 in.) in head circumference. (This is the measurement around the top of the head.)
• Are starting to lose the "baby" look. Your child, who is now in fast motion much of the time, gradually adopts a leaner frame. Your child's head is still large in proportion to the rest of their body. But by 18 months of age, the face is not as "chubby." People may comment that your child is starting to look like a "little boy" or a "little girl."
• Get their first molars. They may also get their canine teeth (also called "eye teeth").
• Don't nap as much in the morning, or they give up this nap time completely. But they still need to sleep about 11 to 14 hours in a 24-hour period.^{footnote 1}

Thinking and reasoning (cognitive development)

Most children by 18 months of age:

• Have formed a sense of self, the ability to see themselves as separate from others. They can now imagine a threat. They often cling to parents and fear strangers.
• Can usually find an object that they watch you move from one place to another. For example, you may hide a teddy bear under a blanket. After your child finds the teddy bear by removing the blanket, they will find it again after watching you move it under a pillow on the couch.
• Start to play pretend. Usually it will be one pretend act at a time, such as giving a stuffed animal a "drink" from a toy cup. (By 24 months, your child may act out a whole process, such as getting "baby" ready for bed.)
• Can point to a body part. For example, when you ask "where's your tummy?" your child will point to it.

Social and emotional development

Most children by 18 months of age:

• Don't show much of an interest in playing with other children. But they engage in "parallel play." This means that children play next to or alongside each other but don't interact. Adults are their main focus for social growth.
• Are very curious. They like to grab and move almost anything within reach.
• Like to show off for parents and caregivers. They may become happy when they do something they are especially proud of and look to parents for a reaction.
• Like to copy what other people do. For example, your child may like to imitate you and stretch their arms up high when you play "so big!" Your child may try to make the same faces you do and copy something you say by jabbering with a similar tone of voice.

Language development

Most children by 18 months of age:

• Understand 10 times more than they are able to put into words.
• Know the names of some people, body parts, and objects. They can often point to an object in a book when asked.
• Use their own language, sometimes called jargon. It's a mix of made-up words and understandable words.

Sensory and motor development

Most children by 18 months of age:

• Stand from a crawling position without holding onto anything.
• Walk by themselves.
• Hold a cup by themselves.
• Can coordinate hand movement between the fingers and the wrist. This allows your child to eat with a spoon. (But at this age, it is guaranteed to be messy.)
• Like to press buttons, move handles, and turn knobs.
• Can stack 4 blocks.