Social and Emotional Developmental Milestones in Children
A child’s development involves more than learning to walk, talk, or recognize numbers. Social and emotional development describes how children learn to understand and express emotions, build relationships, interact with others, develop independence, and respond to social situations (Centre for Early Childhood, n.d.).
These skills begin developing in infancy and continue throughout childhood. They are influenced by children’s individual characteristics as well as their relationships and experiences with parents, caregivers, siblings, teachers, and peers. Responsive, back and forth interactions between children and caring adults (sometimes called serve and return interactions) help build foundations for social skills, emotional well-being, and communication (Center on the Developing Child at Harvard University, n.d.).
Developmental milestones can provide useful guidelines for parents and caregivers. They should not, however, be treated as rigid deadlines. The American Academy of Pediatrics notes that milestone lists support developmental surveillance but are not diagnostic tools (AAP, n.d.).
What is Social and Emotional Development?
Social and emotional development includes a broad range of abilities, including:
Recognizing and expressing emotions
Responding to familiar people
Developing attachments and relationships
Showing affection
Communicating wants and needs
Beginning to understand other people’s feelings
Managing frustration and strong emotions
Participating in play with others
Developing independence
Following social expectations and rules
Taking turns and cooperating
These abilities develop gradually. A baby who smiles at a caregiver is demonstrating an early social skill, while a preschooler who takes turns during a game is demonstrating a more complex social-emotional skill.
Social and Emotional Milestones by Age
Birth to 3 Months: Building Early Relationships
During the first few months of life, babies begin learning that caregivers are sources of comfort, safety, and interaction.
By around 2 months, many babies (AAP, n.d.):
Look at a caregiver’s face
Smile when spoken to or smiled at
Seem happy when a familiar caregiver approaches
Calm when spoken to or picked up
These early interactions may seem simple, but they are important building blocks for relationships. When caregivers respond to a baby’s cries, facial expressions, movements, and sounds, they create opportunities for early social communication.
4 to 6 Months: Increasing Social Engagement
Between 4 and 6 months, babies generally become more socially interactive.
Around 4 months, a baby may (AAP, n.d.):
Smile to gain someone’s attention
Chuckle when a caregiver tries to make them laugh
Look at, move toward, or make sounds to maintain another person’s attention
By about 6 months, many babies (AAP, n.d.):
Recognize familiar people
Laugh
Enjoy looking at themselves in the mirror
Participate in back-and-forth vocal interactions with caregivers
Parents can support this development by smiling back, imitating sounds, talking with the baby, and responding to facial expressions and gestures.
7 to 12 Months: Attachment, Stranger Awareness, and Social Communication
During the second half of the first year, babies often become increasingly aware of familiar versus unfamiliar people.
By around 9 months, many babies (AAP, n.d.):
Show several facial expressions, such as happiness, sadness, anger, or surprise
Become shy, clingy, or fearful around strangers
React when a caregiver leaves
Look when their name is called
Smile or laugh during social games such as peek-a-boo
By 1 year, many children enjoy social games such as pat-a-cake and begin using gestures such as waving goodbye. At this stage, separation reactions can be easily noticeable. A child becoming upset when familiar caregiver leaves does not necessarily indicate a problem, but a part of developing attachment and awareness of familiar relationships.
12 to 18 Months: Affection, Imitation, and Emerging Independence
Toddlers increasingly understand that they can influence their social environment.
Around 15 months, many children (AAP, n.d.):
Show affection through hugs, cuddles, or kisses
Hug a stuffed animal or toy
Clap when excited
Show an adult an object they like
Copy other children during play
By approximately 18 months, many toddlers (AAP, n.d.):
Move away from a caregiver but check to make sure the caregiver is nearby
Point to share something interesting
Participate in simple routines, such as helping with dressing
Looks at books with a caregiver
This period often brings a combination of independence and dependence. A toddler may enthusiastically want to do something alone and then quickly seek reassurance from a parent or caregiver.
2 Years: Recognizing Feelings and Reading Social Cues
Around age 2, children begin developing a greater awareness of other people’s emotions.
Many 2-year-olds (AAP, n.d.):
Notice when another person is hurt or upset
Look at an adult’s face to understand how to respond to an unfamiliar situation
Use gestures to communicate, such as blowing kisses or nodding
Begin participating in simple social interactions
Emotional regulation is still developing at this age. Toddlers can experience strong emotions but have limited ability to control or communicate those emotions. Tantrums and frustrations can therefore be common. Adults can help by naming emotions while maintaining predictable routines and clear boundaries.
30 Months to 3 Years: Parallel Play and Growing Social Interactions
By around 30 months, many children (AAP, n.d.):
Play alongside other children and sometimes play with them
Show others what they can do
Begin recovering from separation from a caregiver more readily
Notice other children and join them in play
By approximately 3 years, many children can participate in increasingly complex social interactions. They may engage in back-and-forth conversations and demonstrate greater interest in playing with other children (AAP, n.d.). Parents and caregivers can encourage these skills by providing opportunities for pretend play, modeling sharing and turn-taking, and helping children put feelings into words.
4 Years: Cooperation, Pretend Play, and Emotional Understanding
Around age 4, children’s social worlds often expand. Friendships, cooperative play, imaginative play, and classroom experiences provide opportunities to practice social and emotional skills.
Children at this age may (AAP, n.d.):
Engage in increasingly cooperative pretend play
Develop preferences for friends or playmates
Begin understanding more complicated and social situations
Practice taking turns and following rules
Becoming increasingly independent while still seeking adult guidance
The AAP’s current developmental guidance also emphasizes that preschool years are an important period for supporting healthy mental, emotional, and behavioral development through relationships, routines, choices, and opportunities for independence (n.d.)
5 Years: Cooperation, Rules, and Social Responsibility
By 5 years, many children are developing more sophisticated social skills.
The CDC/AAP (n.d.) milestone guidance identifies skills such as:
Following rules or taking turns during games with other children
Singing, dancing, or performing for others
Participating in simple household chores
These skills reflect growing independence in the ability to participate in group activities. Children are also continuing to learn how to manage disappointment, resolve disagreements, understand others’ perspectives, and regulate their emotions.
How to Support Social and Emotional Development
Social-emotional development does not require special equipment or expensive activities. Many of the most valuable opportunities happen during ordinary interactions!
Respond to Children’s Cues
When babies make sounds, smile, gesture, or cry, responding with eye contact, words, touch, or facial expressions creates a back-and-forth interaction. The CDC describes these responsiveexchanges as important experiences for developing social and communication skills (n.d.).
Name Emotions
Help children connect words with feelings:
“You look frustrated.”
“You are excited to see grandma.”
“It looks like you are feeling sad.”
Naming emotions can help children gradually develop an emotional vocabulary.
Model Healthy Emotional Behavior
Children learn by observing adults. Demonstrating calm problem-solving, empathy, apologizing after mistakes, and talking about emotions provides children with examples of how relationships work.
Provide Opportunities for Play
Pretend play, games, and interactions with other children allow children to practice cooperation, communication, taking turns, and problem-solving.
Offer Appropriate Choices
Simple choices can support independence:
“Would you like the red cup or the blue cup?”
“Would you like to put your shoes on first or your jacket?”
Maintain Predictable Routines
Consistent routines can help young children understand what to expect and provide opportunities to practice independence.
Make Time for Connection
Reading together, eating meals, playing, singing, and participating in everyday routines can all provide opportunities for social-emotional learning
When Should Parents Be Concerned?
Children develop at different rates, and one difference from a milestone checklist does not necessarily mean that a child has a developmental concern. However, parents and caregivers should discuss any concerns with a pediatrician or other qualified healthcare professional when they notice persistent differences, have questions about development, or observe that a child has lost a skill they previously had.
Developmental surveillance is an ongoing process rather than a one-time assessment. The AAP recommends developmental surveillance at doctor appointments and standardized developmental screening at 9, 18, and 30 months old, with ASD specific screening at 18 and 24 months (AAP 2, n.d.). Additional screening may be appropriate whenever a parent or professional raises a concern (AAP, 2020; Zubler, 2022).
It is also important to remember that milestone checklists are not diagnostic tests. The AAP notes that social-emotional milestones have historically had less normative research data than some other developmental areas (AAP, 2020).
Supporting the Whole Child
Social and emotional development begins in infancy and continues throughout childhood. A child’s first smiles, attachment to caregivers, emotional expressions, pretend play, friendships, cooperation, and growing independence are all parts of this developmental journey. Parents and caregivers can support these skills through responsive relationships, play, conversation, predictable routines, emotional coaching, and opportunities for age-appropriate independence.
Most importantly, developmental milestones should be viewed as guides rather than deadlines! The goal is not to compare children or create anxiety about whether a child is “on schedule.” Instead, milestones can help adults notice children’s strengths, understand emerging skills, and recognize when additional support may be helpful.
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References
American Academy of Pediatrics. (n.d.). Developmental milestones. Retrieved September 29,
American Academy of Pediatrics 2. (n.d.). Developmental surveillance and screening patient
care. Retrieved September 29, 2026, from https://www.aap.org/en/patientcare/developmental-surveillance-and-screening-patient-care/
American Academy of Pediatrics. (2020). Promoting optimal development: Identifying infants
and young children with developmental disorders through developmental surveillance
and screening. Pediatrics, 145(1), e20193449. https://doi.org/10.1542/peds.2019-3449
Center on the Developing Child at Harvard University. (n.d.). Serve and return: Back-and-forth
exchanges. Harvard University. Retrieved September 29, 2026, from
https://developingchild.harvard.edu/key-concept/serve-and-return/
Centre for Early Childhood. (n.d). What is social and emotional development. Retrieved
September 29, 2026, from https://centreforearlychildhood.org/why-this-matters/what-issocial-and-emotional-development/
Zubler, J. M., Whitaker, T. M., Volpe, M. M., Mistretta, K. E., Taylor, C. A., & Shaw, J. S.
(2022). Evidence-informed milestones for developmental surveillance tools. Pediatrics,
149(3), e2021052138. https://doi.org/10.1542/peds.2021-05213