Zengakuren is a league of university student associations founded in 1948 in Japan. The word Zengakuren (全学連) is an abridgement of Zen Nihon Gakusei Jichikai Sō Rengō (全日本学生自治会総連合) which literally means "All-Japan Federation of Student Self-Government Associations." Notable for organizing protests and marches, Zengakuren has been involved in Japan's anti-Red Purge movement, the anti-military base movement, the Anpo protests against the U.S.-Japan Security Treaty, the 1968–1969 Japanese university protests, and the struggle against the construction of Narita Airport.

The Red Purge was an anticommunist movement in occupied Japan from the late 1940s to the early 1950s. Carried out by the Japanese government and private corporations with the aid and encouragement of the Supreme Commander for the Allied Powers (SCAP), the Red Purge saw tens of thousands of alleged members, supporters, or sympathizers of left-wing groups, especially those said to be affiliated with the Japanese Communist Party, removed from their jobs in government, the private sector, universities, and schools. The Red Purge emerged from rising Cold War tensions and the Red Scare after World War II, and was a significant element within a broader "Reverse Course" in Occupation policies. The Red Purge reached a peak following the outbreak of the Korean War in 1950, began to ease after General Douglas MacArthur was replaced as commander of the Occupation by General Matthew Ridgway in 1951, and came to a final conclusion with the end of the Occupation in 1952.