The technique of mechanical alloying, although originally developed to produce oxide-dispersion-strengthened superalloysfor aerospace and high-temperature applications, is now recognized as an important and versatile technique to synthesizemetastable and advanced materials with a high potential for widespread applications. Mechanical alloying involves repeatedcold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. The reduced difusion distancesbetween metal powder layers formed as a result of heavy deformation, introduction of a high density of crystal defects, and aslight rise in powder temperature contribute to alloy formation from blended elemental powders. The type of phases/materialsproduced by mechanical alloying of powder mixtures include supersaturated solid solutions, intermetallics, quasicrystallinealloys, high-entropy alloys, amorphous alloys, and composites. If the material produced is crystalline in nature, most oftenthe grain size is in the nanometer size. Amongst these phases, nanostructured materials and nanocomposites have been themost important types investigated. In this contribution, we will present an overview of the processing, characteristics, andproperties of nanocrystalline materials and nanocomposites produced by mechanical alloying, with special emphasis on ourrecent work.