When Your Toddler Says “No”

- It’s Not Defiance, It’s Development

Toddlers often refuse baths, meals, or even the toy they begged for just minutes ago. While it may feel like they’re testing your patience, brain science shows something different: your child isn’t being defiant - they’re discovering who they are.

Developmental psychologist Margaret Mahler found that between 18 and 36 months, toddlers start realizing they are separate people from their parents. Every “no” is a boundary, a way to explore where they end and you begin.

Inside a developing toddler’s brain, two systems are at odds:

• The limbic system, driving emotions and desire for autonomy, is fully active.

• The prefrontal cortex, responsible for impulse control, is still developing.

The result? They want independence but don’t yet have the tools to manage it. Every “no” is a test: Do my choices matter? Am I my own person? It’s messy, exhausting, and absolutely necessary.

Researchers Grolnick and Ryan found that supporting autonomy builds motivation and emotional regulation. When toddlers feel their choices matter, they grow more self-driven, confident, and secure. Conversely, dismissing their “no” teaches them their voice doesn’t count - and they either stop using it or escalate it.

The key is not to let them “run the show,” but to offer choices within limits:

• “Red bowl or blue bowl?”

• “In 5 minutes, bath time.”

• “Walk or be carried?”

Ground yourself when the power struggle starts. Acknowledge their feelings: “You really don’t want to leave,” then hold your limit: “And it’s time to go.” Give them agency within the boundary.

Every “no” is a step toward individuality. When your toddler pushes back, they’re not rejecting you - they trust you enough to test the limits safely. Supporting their emerging autonomy builds confidence, resilience, and a strong sense of self.