Unmake the bed and remove all sheets. Adjust the mattress pad so it covers the top of the mattress evenly. If the pad has elastic sides that grip the mattress, make sure each corner is stretched over the mattress.
Place a mattress cover or protector over the mattress and pad. Stretch the edges and excess amount of cover or protector over the corners and sides of the mattress. If the pad still slides proceed to Step 3.
Remove the cover or protector and pad. Cut a rubber or latex rug pad to a size slightly smaller than the mattress.
Place the rug pad on the center of the mattress. Place the mattress pad on top. You can use safety pins to pin the edges of the mattress pad to the edges of the top of the mattress for extra stability.
Replace the mattress cover or protector. Replace the bedding and sheets.