California law says a child should be in a booster seat until the age of 6 or weighs 60 pounds. However, there has been talk about extending the requirement to 8 years old or 80 pounds. My daughter is 6 1/2 and fits in her booster just fine. I don't think we will be taking her out anytime soon. I did find a 5-step test to determine if your car's seatbelt will fit your child properly.
If you answer no to any of these, she/he still needs a booster:
1. Does the child sit all the way back against the vehicle's seat (no slouching)?
2. Do the child's knees bend comfortably at the edge of the vehicle's seat?
3. Does the belt cross the shoulder between the neck and arm?
4. Is the lap belt as low as possible, touching the thighs?
5. Can the child stay seated like this for the whole trip?