Desks are, for the most part, more solidly constructed than chairs or tables, and they don't wobble as easily, but when one does, it can be disconcerting. You might find your fingers missing strokes on the keyboard, and the desk drawers may not open and close as easily as they should. You often can restore stability by tightening the fasteners, but some wobbles are because of dips in the floor, so you may have to modify the lengths of the legs. You can also reposition the desk; it's a proven fact that rotating the desk can stop it from shaking.
Tightening the Desk
Remove as many items as you can from the drawers to make them lighter; then pull them out and set them aside. If any drawer wobbles, empty it so you can tighten it.
Crawl under the desk with a screwdriver and a flashlight; look for loose fasteners and tighten them. Many desks are assembled with corner brackets or strips of metal that act as braces, and the screw holding these back out. If you don't see metal brackets, look for hardwood strips and tighten any screws you see in them.
Look for a bolt in each of the top corners of the desk that holds the leg to the frame and tighten the nut with a wrench. These bolts are more common on tables than they are on desks, but your desk probably has them if the legs have no other form of bracing.
Re-glue broken glue joints with carpenter's glue. Tap a loose joint apart with a rubber mallet, spread glue on the male part of the joint, and reassemble it. Wrap a strap clamp around the desk and tighten it with the ratchet to draw the joint together. If more than one joint is loose, glue them all at the same time so you only have to clamp the desk once.
Fix wobbly drawers by tightening screws with a a screwdriver and re-gluing loose glue joints. You may have to knock the entire drawer apart to re-glue it properly. Hold it together with bar clamps or a strap clamp while the glue sets.
Adjusting the Legs
Measure the length of each leg with a tape measure to ensure they are all the same. If one is shorter than the others, glue a wooden shim to the bottom with carpenter's glue.
Adjust the feet -- if the desk has adjustable feet -- by turning the one on the leg counterclockwise that isn't in contact with the ground to lengthen it.
Re-orient the desk to stop it from wobbling because of an uneven floor. You are guaranteed to find a stable position if you rotate the desk around its center, says JR Minkel, reporting in "Scientific American" in 2007. If the floor has a severe tilt, however, the most stable position for the desk may be one in which it isn't level.