Remove the mattress and mattress support from inside the crib. Lift each corner of the mattress support out of the locking tabs on the crib rail to remove it.
Use an Allen wrench to remove the contour bar from the top of the front side of the crib. The bar secures with an Allen bolt on each end. Remove the front rail by removing the four Allen bolts that secure the rail to the crib, two on each side.
Remove one end panel from the crib using the Allen wrench to remove the two bolts that secure it to the back rail. Repeat this process to detach the back rail from the opposite end panel as well. Set the end panels aside.
Attach the full-size bed rails to the front and back rail. Place the back rail in the headboard position and the front rail at the foot of the bed. Secure the bed rails in the slots on the headboard and foot board, lining up the hooks on each end of the rails with the slots. Push the rails down toward the floor to lock them into place.