Remove the mattress from the crib. Unhook the crib floor and lower it to the lowest possible setting.
Remove the four screws securing the front side using a Phillips screwdriver. There are two screws on each side, one on the top and one on the bottom. Set the front side out of the way.
Align the toddler bed rails on the mounting rail underneath the crib floor. Attach the rails to each end of the crib with screws, tightening them with a Phillips screwdriver.
Replace the crib mattress. Store the side railing out of the way.