By 1933, he was able to organise a meeting attended by 1000 members of the youth wings of the Communist Party and the Section française de l'Internationale ouvrière.
He concluded that it could not be defended, as Trotsky held, as a degenerated workers' state but that it was a bureaucratic collectivist system, an idea that he introduced to Trotskyism.
During World War II, he was pronounced unfit for duty, and attempted, with Marcel Hic, to publish La Verité secretly.
Craipeau temporarily withdrew from politics, and in 1951, he moved to Basse-Terre in Guadeloupe, where he became a school teacher and soon secretary of the National Education Federation trade union.
He remained a leading member of this party for many years, during which he wrote numerous books on left-wing politics and revolution.