When should I move my child from a crib to a toddler or big-kid mattress?

Many children transition from a crib to a toddler or big-kid bed between 18 months and 3 years, often when they start climbing out of the crib or show interest in a bigger bed. Readiness signs, safety, and your child's temperament matter more than a specific age. Always follow your pediatrician's guidance and your own safety judgment.