This paper reviews the current state of knowledge and practice in highwall mining. Highwall mining has become a widely applied method in surface mining. It is commonly used alone or in conjunction with contour or slot mining. It provides 800 to 1,200 ft of additional recovery when, in contour mining, the economic stripping ratio is reached or, in slot mining, when surface access to a reserve is limited. A significant attribute of the highwall miner is its versatility. Highwall mining has been used successfully to mine (1) abandoned prereclamation law highwalls, (2) points or ridges uneconomic to mine by underground or other surface methods, (3) outcrop barriers left adjacent to underground mines, (4) separate benches of the same seam where the parting thickness or quality differences between benches render complete extraction uneconomic, (5) previously augered areas containing otherwise inaccessible additional reserves, and (6) close or widely spaced multiple seams. The theory and design methods to assess roof, pillar, and floor stability are presented, followed by three case histories.