The present invention provides an adjustable child restraint device, namely, a juvenile safety seat. The safety seat preferably includes a backrest and a pair of side guards that protect the body and shoulder of a person, such as a small child. Each of the pair of side guards have a top end and a bottom end and each are respectively pivotally connected about an axis to the backrest at their bottom ends and movable between a closed position and an open position so that the distance between the respective bottom ends of the side guards remains substantially constant and the distance between the respective top ends of the side guards is adjustable by pivoting movement of the side guards. A curved guide means is disposed in communication with the side guards for guiding movement of the side guards.