This article examines Soviet perceptions of subversive and military threats from Poland to the Soviet Union in the 1920s and early 1930s. Drawing on archival materials from the Soviet foreign ministry, Communist Party leadership and security organs, it shows how the Soviet leadership held exaggerated fears about Polish threats to the Soviet western border regions and military intervention. A pattern of misperception stemmed from the Bolshevik defeat to Poland in the 1919-1920 Soviet-Polish War, which rather than moderating the early Soviet regime ultimately encouraged more widespread use of state violence and provided further rationale for Stalin's 'Revolution from Above'.