Last updated:
April 1, 2026
Summary of important social milestones
| Age | Milestones |
|---|---|
| 1 month old | Prefers human faces, reacts to voice, and establishes eye contact |
| 2 months old | Social smile |
| 4 months old | Sustained social smile, laughs |
| 6 months old | Prefers caretaker, stranger anxiety starts |
| 9 months old | Object permanence; recognises their name; consonant babbling |
| 1 year old | Tantrums typically begin |
| 16 months old | Hugs parents |
| 18 months old | Kisses with a pucker; may recognise themself in the mirror |
| 2 years old | Parallel play |
| 2.5 years old | Imaginative play; uses pronouns; tantrums peak |
| 3 years old | Knows age and sex; some understanding of fairness |
| 4 years old | Together play, potty training, and sexual modesty |
| 5 years old | Inquisitive; communicates in full sentences; concrete sense of rules |
Overview of social development
Social development begins at birth with attachment to the caretaker, especially in the form of mother-infant bonding during breastfeeding.
- Abnormalities in social development might be a sign of:
- Underlying emotional issues
- Neglect
- Abuse
- Underlying medical issues
- Neurodevelopmental disorders, e.g., autism
- Hearing impairment – language acquisition will also be impaired
- Underlying emotional issues
Social developmental milestones
- Newborn to 1 month
- Preference for human face
- React to voice at one month of age
- Crying peaks around 6 weeks of age (up to 3 hours per day)
- Should re-attain birthweight by 2 weeks and grow 30g/d until 4 months
- 2 months of age
- Social smile
- Will listen to the voice and make a cooing sound
- 4 months of age
- Sustained social smile and laughing
- The infant will begin to show distinct facial expressions in various scenarios
- May show displeasure if social contact is broken
- Recognises the sight of food and often becomes excited
- Growth slows to 20g/d until 1 year of age (birthweight should have doubled)
- 6 months of age
- An infant typically prefers their mother or primary caretaker
- Stranger anxiety begins to develop. This can be directed towards you, the doctor.
- Peak-a-boo is often fun for the child, as object permanence has not yet developed
- 9 months of age
- Object permanence has developed. This makes the separation more difficult as the child realises the caretaker has not disappeared, but is gone
- Increased wariness of strangers
- Monosyllabic babbling
- Should recognise and respond to the name
- Should understand “bye-bye” and may wave
- 12 months of age
- Should be able to say and understand a few words other than “mama” or “dada”
- Makes postural adjustment to dressing
- May be able to respond to commands such as “give me”
- Tantrums often begin (tantrums lasting longer than 15 minutes or occurring more than 3 times/day may reflect underlying medical, emotional, or social problems)
- Birthweight should have tripled
- 16 months of age
- Baby should start to hug parents and show a high preference for familiar people for comfort
- Preference towards strangers is particularly concerning for potential neglect or abuse
- 18 months of age (1.5 years)
- Able to kiss a parent with a pucker
- May exhibit self-awareness and may recognise themself in the mirror
- Should indicate some desires by pointing
- 24 months of age (2 years old)
- Linguist development expands. Vocabulary has usually expanded to 50-100 words and will dramatically increase after 2 years of age
- Should be able to properly use a spoon
- Should be able to respond to two-step commands
- Engaged in parallel play
- 30 months of age (2.5 years old)
- Child begins to engage in imaginative play, but may have difficulty distinguishing reality from fantasy
- Tantrums peak at 2.5 years of age
- Refers to self as “I” and “me”
- Birthweight should have quadrupled
- 3 years old
- Should be able to help with getting dressed
- Washes hands
- Should know age and sex, and be able to tell someone his/her name when asked
- Still not able to consider others’ points of view (egocentricism), and fairness is viewed in somewhat concrete terms (everyone gets the same)
- 4 years old
- Social interaction and together play should have started
- Control of bowel and bladder has developed, and potty training is likely accomplished by this age
- Bed-wetting is normal in girls up to 4 years and boys up to 5 years
- Children should begin to show modesty about sexual organs and nudity
- 5 years old
- Dresses and undresses themself
- Inquisitive (asks about meanings of words)
- Should be able to communicate in complete sentences that are understood by strangers
- A child should develop a sense of rules (only understood in concrete terms)
- Genital self-touching is still considered normal (but the child should know when it is not appropriate)
- Excessive sexualised behaviour or acting out adult sexual acts is a troubling sign and may indicate psychiatric issues or abuse