The first time your baby smiles back can feel like a tiny conversation. Soon, those exchanges grow into giggles, games and gestures that show how your child connects with people. Baby social development milestones are the everyday signs of that growing connection, from watching your face to inviting you into play.
These behaviours develop alongside communication and thinking. The ages below are guides, not deadlines. Look for changes over time during familiar routines.
Birth to 2 months: faces, voices and first smiles
Newborns rely on adults to help them feel safe. They may study your face at close range, become calmer when you speak or pick them up, and gradually show more interest when you approach.
By around two months, many babies smile in response to someone talking or smiling at them. This is often called a social smile. A baby may also smile during sleep, but a responsive smile happens during an exchange. You smile, pause, and your baby answers with their own expression.
Hold your baby comfortably where they can see your face. Speak gently, wait and notice whether they look towards you or change expression. No special toy is needed.
3 to 4 months: your baby starts the conversation
Social exchanges often become more deliberate. Your baby might smile to attract attention, chuckle when you play, or make sounds as if asking you to continue. They are discovering that their actions can change what another person does.
This is an important part of infant social development: interaction is no longer only something adults initiate. If they coo, copy the sound once and pause. An answering sound, smile or wriggle is their turn in the conversation.
5 to 6 months: familiar people and shared enjoyment
Around six months, many babies recognise familiar people, laugh and enjoy watching themselves in a mirror. You might notice a bigger reaction when a favourite carer enters the room or a delighted squeal during a familiar song.
Babbling and social play begin to overlap. Your baby may make a sound, watch your response and try again. This back-and-forth helps lay foundations for communication, although it is not yet a spoken conversation.
For an easy game, sing the first line of a nursery rhyme, pause before a familiar action, then finish it with a smile. Watch for anticipation rather than expecting copied words.
7 to 9 months: reactions, preferences and peek-a-boo
By about nine months, many babies look when their name is called, display varied facial expressions and laugh during peek-a-boo. They may reach towards you when you leave or become cautious with unfamiliar people.
Wariness around strangers or distress during separation can surprise parents whose baby was previously happy with everyone. The NHS explains that separation anxiety and fear of strangers are common from around six months onwards. They often reflect greater awareness of familiar caregivers rather than a setback.
Play peek-a-boo slowly so your baby can predict your return. If they turn away or seem overwhelmed, stop and comfort them. Their response matters more than completing the game.
10 to 12 months: gestures and joining in
As the first birthday approaches, play becomes increasingly shared. Many babies enjoy simple games such as pat-a-cake by twelve months. Waving goodbye may appear, and some begin showing or offering objects to involve another person.
Notice what happens when your baby drops a spoon, then looks towards you. The action may be an experiment with cause and effect, an invitation to repeat a funny moment, or both. Social and cognitive skills often work together.
If you are tracking baby interaction milestones, record what your child does rather than testing them. Observations across several days are more useful than prompting the same gesture repeatedly.
12 to 18 months: imitation, affection and shared attention
During the second year, social play gains variety. By around fifteen months, many children clap when excited, show an adult something interesting, imitate other children during play and show affection through cuddles or kisses.
Closer to eighteen months, you may see your toddler move away to explore and then check that you are nearby. Pointing to share interest, rather than only to request something, is another meaningful development.
These changes show that relationships are becoming more complex. Your child is learning to share experiences and notice how others respond.
How to spot social progress in ordinary routines
You do not need a milestone chart open throughout the day. Watch for three things: who starts an interaction, how your baby responds, and whether the exchange continues.
At nappy-changing time
Say a familiar phrase before lifting your baby’s legs, then pause. A smile, excited movement or anticipatory look suggests they are beginning to recognise the routine and your part in it.
With a picture book
Point to a picture, name it and wait. A younger baby may look at your face. An older baby might alternate their gaze between you and the page or help turn it. Both are forms of shared attention.
During a family meal
Notice whether your baby looks towards a speaker, reacts to laughter or copies a clap. Resist demands to perform for relatives. Children often show their clearest skills when comfortable.
For related developmental changes, explore our guides to baby communication milestones, baby cognitive development and separation anxiety in babies.
When should parents seek advice?
All babies develop differently, and prematurity can affect how ages are interpreted. If your baby was born early, ask your health visitor whether to use their corrected age.
Speak to your health visitor or GP if your baby rarely responds to faces, voices or social approaches, does not develop expected social behaviours, or loses a skill they previously used. Concerns about hearing, vision or responsiveness also deserve attention. You need not wait for a scheduled review.
In the UK, routine child health reviews are opportunities to discuss development. Explain what you notice, when it happens and whether the pattern is changing. A milestone alone cannot diagnose a developmental condition.
Frequently asked questions
When do babies start smiling socially?
Many babies begin smiling back at a face or voice by around two months. Earlier smiles can occur without social interaction. If concerned, discuss your baby’s responses with your health visitor.
Does my baby need to make constant eye contact?
No. Babies naturally look away when tired, distracted or overstimulated. What matters is their broader pattern of engagement, not continuous eye contact or a single moment.
Is separation anxiety a normal social milestone?
Yes. It commonly develops from around six months and can continue into toddlerhood. Reassurance, predictable goodbyes and familiar caregivers can help your child feel secure.
How can I encourage social skills without pushing milestones?
Follow your baby’s interests, talk face to face, respond to sounds and play simple turn-taking games. Short, enjoyable interactions are more valuable than testing a particular action.
Watching connection grow
The most useful way to understand baby social milestones is to notice exchanges that build on one another: a glance becomes a smile, a smile becomes a game, and a game becomes shared attention. Give your child time to respond, enjoy the moments they initiate and seek guidance whenever something worries you.