Società Costruzioni Industriali Milano, better known as Socimi, was an Italian manufacturing company based in Milan. It was a manufacturer of trams, metro trains; traction motors for these and for trolleybuses; and bodies for motorbuses and trolleybuses. It also manufactured weapons, such as rifles. The company was founded by Alessandro Marzocco in 1969 and declared bankruptcy in 1994 due to its involvement in the Mani pulite scandal in 1992.
Trolleybus systems which purchased Socimi trolleybuses included the systems of Cagliari, Milan, Modena and Salerno. The company supplied trams only to Rome, but collaborated with Bombardier Transportation in the development of the Eurotram for the Strasbourg tramway in France. Heavy rail trains produced by Socimi included the FNM Socimi coaches for Ferrovie Nord Milano as well as EMU300 trains for Taiwan Railway Administration.
SOCIMI produced the Socimi Type 821 submachine gun in the 1980s.