Attach double-sided cloth tape to the underside of the rug. Measure the edges of the rug using a tape measure, and cut the proper lengths of tape. Place the tape a couple of inches inside the edge of the rug, then lay the rug down and smooth it out.
Attached Velcro pads to the underside of the rug if it is placed on top of carpeting. These are cut and installed in the same way as the two-sided tape. The Velcro hooks dig into the carpet, preventing slippage.
Place an anti-slip rug mat underneath the rug. These can be purchased from any good home wares store. Buy one that is a few inches smaller than the rug, lay it down on the floor and place the rug on top of it.
Apply a layer of spray-on adhesive to the underside of the rug and lay it down on the floor. A variety of products are available, from spray-on rubber adhesive to foams.