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Child behaviour by age

Published on January 26, 2026 at 13:40 / Updated on January 26, 2026 at 21:34

From as early as 18 months, a child may begin to display behaviours that feel unsettling for parents as autonomy starts to emerge. This phase, often referred to as the “terrible twos,” can include tantrums, anger, mood swings, opposition, and frustration. Although this period can be challenging, it is a normal part of development.

Children aged 2, also known as the “terrible twos”

The “terrible twos”, which can extend from 18 to 36 months, mark an awakening of autonomy. At this stage, the child feels a strong desire for independence and wants to do more things on their own, despite still having very limited abilities.

Because language development is not yet complete, this gap often leads to emotional and behavioural outbursts such as tantrums, anger, opposition, and frustration. The child struggles to clearly express their needs, which can intensify emotional reactions.

Parents may feel overwhelmed when faced with a child who was previously calm and cooperative. It is important to remember that the child is not intentionally challenging authority. This phase is rooted in exploration and learning.

Children aged 3

Around the age of 3, children begin to display behaviours that may resemble those seen during adolescence. They can argue, question rules, and oppose everyday expectations. Emotions such as joy, anger, fear, and sadness are often felt more intensely, yet they lack the tools to fully understand or regulate them.

These behaviours are closely linked to the child’s language development. As communication skills and imagination expand, children are better able to put words to their desires, preferences, and intentions.

Children aged 4

At age 4, children go through an intense developmental phase marked by an even stronger desire for autonomy and independence. While self-control continues to improve, emotional storms can still occur.

This stage involves emotional and identity development, during which children may test limits, negotiate at length, and experience more complex emotions. Fatigue, transitions, and changes are common triggers for challenging behaviors.

During this period, consistency and clarity in rules and limits are essential. A stable and predictable framework helps create a sense of safety for the child.

Supporting parents through early childhood

Parental guidance and structure play a key role in the healthy development of children aged 2, 3, and 4.

A few simple strategies can help parents navigate this stage more smoothly:

  • Acknowledge the child’s emotions, even the most intense ones, without dismissing or minimizing them. Help the child identify and name what they are feeling.
  • Create a reassuring framework by setting clear, consistent, concrete, coherent, and meaningful limits and rules, often referred to as the 5C method (learning to say “no” to children).
  • Adjust expectations to the child’s actual age. There can be a gap between what parents expect and what a child is emotionally and cognitively capable of at this stage.
  • Establish a stable and predictable routine, allow time for play, and ensure the child gets enough sleep. This approach all support healthy development.

Early childhood stages can vary greatly from one child to another, as each child has their own personality and pace of development. However, if a child’s behaviours seem excessive or persist over time, consulting a healthcare professional is recommended.

Text written in collaboration with Vie de Parents

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