The Birmingham Small Arms Company Limited (BSA) was a major industrial combine, a group of businesses manufacturing military and sporting firearms; bicycles; motorcycles; cars; buses and bodies; steel; iron castings; hand, power, and machine tools; coal cleaning and handling plants; sintered metals; and hard chrome process.

At its peak, BSA was the largest motorcycle producer in the world. Loss of sales and poor investments in new products in the motorcycle division, which included Triumph Motorcycles, led to problems for the whole group.

A government-organised rescue operation in 1973 led to the takeover of remaining operations by what is now Manganese Bronze Holdings, then owners of Norton-Villiers, and over the following decade further closures and dispersals. The original company, The Birmingham Small Arms Company Limited, remains a subsidiary of Manganese Bronze but its name was changed in 1987.

BSA Guns still exists as an Air Gun manufacturer.