6th » Myra Hindley and Ian Brady are sentenced to Life imprisonment (England and Wales) known as life imprisonment for the Moors murders in England.
8th » A plane crash at Connellsville, Pennsylvania kills Pennsylvania Attorney General, Walter E. Alessandroni, his wife, and other state officials.
16th » The Communist Party of China issues the "Cultural Revolution 1966: The 16 Points and the Red Guards known as May 16 Notice", marking the beginning of the Cultural Revolution.
21st » The Ulster Volunteer Force declares war on the Irish Republican Army (1922–69) or Irish Republican Army in Northern Ireland.
25th » The first prominent Big-character poster known as dàzìbào during the Cultural Revolution in China is posted at Peking University.
26th » British Guiana gains independence, becoming Guyana.
30th » The former Democratic Republic of the Congo or Congolese Prime Minister, Évariste Kimba, and several other politicians are publicly executed in Kinshasa on the orders of President Mobutu Sese Seko or Joseph Mobutu.
30th » Launch of 'Surveyor 1', the first US spacecraft to land on an extraterrestrial body.