Mechanical alloying is a method of synthesis of advanced materials, often with non-equilibrium structures, and, remarkably, of crystalline materials with nanometersized grains. Grinding is also a way of inducing or activating chemical reactions. After having described some general characteristics and some applications of high-energy ball-milling, we sketch out some contributions which Mossbauer spectroscopy has made to gaining a deeper understanding of synthesis mechanisms and of mechanosynthesized materials.