Aluminum casting alloys are the most versatile of all common foundry alloys and generally have the highest castability ratings. This Article discusses the designation and classification of aluminum casting alloys based on their composition and the factors influencing alloy selection. Alloys discussed include rotor alloys, commercial duralumin alloys, premium casting alloys, piston and elevated-temperature alloys, general-purpose alloys, magnesium alloys, aluminum-zinc-magnesium alloys, and bearing alloys. Six basic types of aluminum alloys developed for casting include aluminum-copper, aluminum-copper-silicon, aluminum-silicon, aluminum-magnesium, aluminum-zinc-magnesium, and aluminum-tin. The Article also describes the main casting processes for aluminum alloys, which include die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, and investment casting. In addition, the Article discusses factors affecting the mechanical and physical properties, microstructural features that affect mechanical properties, the effects of alloying, and major applications of aluminum casting alloys.