The Pact of Steel (German: Stahlpakt; Italian: Patto d'Acciaio), known formally as the Pact of Friendship and Alliance between Germany and Italy, was an agreement between Fascist Italy and Nazi Germany signed on May 22, 1939, by the foreign ministers of each country and witnessed by Count Galeazzo Ciano for Italy and Joachim von Ribbentrop for Germany.

The Pact consisted of two parts: the first section was an open declaration of continuing trust and cooperation between Germany and Italy while the second, a "Secret Supplementary Protocol" encouraged a union of policies concerning the military and economy. However, certain members of the Italian government, including the signatory Ciano, were opposed to the Pact.^{[citation needed]}

It was Italian leader Benito Mussolini who dubbed the agreement "the Pact of Steel", after being told that its original name, "the Pact of Blood", would likely be received poorly in Italy.

Generally, the Pact of Steel obliged Germany and Italy to aid the other country immediately, militarily or otherwise, in the event of war being declared, and to collaborate in military and wartime production. The Pact ensured that neither country was able to make peace without the agreement of the other. The agreement was based on the assumption that a war would occur within three years. When Germany invaded Poland on September 1, 1939, and war broke out on September 3, Italy was not yet fully prepared for conflict, and had difficulty meeting its obligations. Consequently, Italy did not enter World War II until June 1940 with an aborted invasion of southern France.