Measure the thickness of the wood on the front panel of the drawer where you plan to install the lock. Purchase an exterior-style lock in the appropriate size from your local hardware store.
Place the two parts of the lock on the outside and inside of the drawer panel where you want to attach them. Draw an outline of the lock pieces with a pencil and mark spots for the screws to be inserted.
Drill holes for the screws, using a bit that is smaller in diameter than the screws you are using. Fit the front piece of the lock onto the drawer and secure it with screws and a screwdriver.
Drill holes into the back of the drawer panel to correspond with the holes for the rear piece, or the bolt, on the lock. Position the piece on the back and secure it with screws, ensuring that the back piece lines up with the front piece.
Close the drawer and test it with the key to the lock.