Constant met Karel Appel and Corneille in 1948 and with them, plus Dotremont, Noiret and Asger Jorn, founded the Cobra group. He had first made international contacts with like-minded artists in Paris in 1946 and along with Dotremont was the major theorist of the group. In his work, which as early as 1946 is already characterised by experimental forms and techniques, the fantasy creatures with large eyes and crude limbs that came to epitomise the Cobra idiom are already there. While Karel Appel and Corneille had an international breakthrough with their work, Constant remained the ideologist of the group.