When can you sit in a booster seat that has a back on it?

Children can typically transition to a booster seat with a back when they outgrow their forward-facing car seat, usually around 4 years old and at least 40 pounds. It's important for them to be mature enough to sit properly in the booster seat without slouching or leaning out of position. The booster seat should be used until the vehicle's seat belt fits correctly, typically when the child is about 4 feet 9 inches tall, around 8 to 12 years old. Always refer to local laws and regulations regarding child passenger safety for specific guidelines.