Early on, the personal friendship and scholarship of Louis Grodecki was formative to his art historical methodology.

During this first phase in the United States, he met Meyer Schapiro[5] and became a friend of the German émigrés Erwin Panofsky, Walter Friedländer and Richard Krautheimer.

There he developed an interest in Pop Art, particularly in the works of Robert Rauschenberg, Claes Oldenburg and Andy Warhol.

In 1970, after having published his best known book on Gothic Sculpture in France (English edition, 1971), he was appointed director at the Zentralinstitut für Kunstgeschichte, Munich.

In the 1970s he read Marc Bloch and had contacts with Georges Duby and closure with Jacques Le Goff, which essentially changed his work.