Mississippi Code Title 63. Motor Vehicles and Traffic Regulations § 63-7-301

(1)(a) Every person transporting a child under the age of four (4) years in a passenger motor vehicle, and operated on a public roadway, street or highway within this state, shall provide for the protection of the child by properly using a child passenger restraint device or system meeting applicable federal motor vehicle safety standards.

(b) Every person transporting a child in a passenger motor vehicle operated on a public roadway, street or highway within this state, shall provide for the protection of the child by properly using a belt positioning booster seat system meeting applicable federal motor vehicle safety standards if the child is at least four (4) years of age, but less than seven (7) years of age and measures less than four (4) feet nine (9) inches in height or weighs less than sixty-five (65) pounds.

(c) If more than two (2) children who are required under subsection (1) of this section to use a booster seat are being transported in a vehicle at one time, and the vehicle only has two (2) lap and shoulder belts in the rear seat, then only the two (2) children sitting in the seats with the lap and shoulder belts are required to use a belt positioning booster seat system and safety belt, and any other children may be secured with a safety seat lap belt only.