Vantongerloo was associated with several mid-century groupings of abstractionists, and showed a strong sense of the utopian and the mathematical. Meeting van Doesburg, Mondrian and van der Leck, he collaborated with them on ‘de Stijl’ magazine. He was a co-founder, with Pevsner, Gabo and Kupka, of the group ‘Abstraction-Création’. Both Mondrian and Pevsner became close friends; Taeuber-Arp, Hélion, Gleizes and Torres-García were other Paris colleagues. Kelly befriended him in post-war Paris, while Bill, his lifelong friend, organised several exhibitions for him, and ensured the survival of his archive after his death.