In September 1940, Aboulker founded a resistance network in Algiers, in partnership with his cousin Roger Carcassonne who had done the same at Oran, and Aboulker subsequently became one of the main leaders of the resistance movement in pro-Nazi Vichy Algeria. The two cousins met Henri d'Astier de la Vigerie, with whom they prepared to support the expected Allied landings in North Africa, in collaboration with Colonel Germain Jousse and the U.S. Consul Robert Murphy, President Roosevelt's representative in Algiers. The headquarters for the preparation were at his father's house at 26 Rue Michelet.