This study aims at offering a new interpretation of the evolution of the Italian stay-behind network «Gladio» by systematically integrating a vast range of Italian and foreign archival sources and by focusing the analysis on the changes that took place in three key factors: «Gladio»’s organizational structure, its operational concept, and the influence of international actors. The article shows that, based on the available sources, during the period in which it was active, between approximately 1951 and 1990, «Gladio» was not manipulated by US intelligence or NATO, and did not perform significant internal security operations to counter communist forces; by contrast, it consistently operated as an instrument of national security policy and defense against external enemies.