Born in Switzerland, to a wealthy Greek family, he studied law and started as a poet, before becoming one of the most prominent art critics of the 20th c. In 1935, he went to Paris, joined the surrealist movement and Andre Breton referred to him as one of the most brilliant minds of our times. In 1939 he moved to the USA, where he reunited with the emigre surrealists and in 1940 he wrote a review for R. Matta, which launched his career as an art critic. After the war, he joined the research program of Columbia University -Studies in Contemporary Culture- along with Margaret Mead. He was also professor of art history at the Farleigh Dickinson University, the art critic for the Village Voice and a regular contributor to the prestigious magazines: Arts Magazine, Art forum, Art in America.

Nicholas Calas formulated a new approach to art criticism, which placed an emphasis on the political, social and historical analysis of the work. Carrying with him the humanism of his heritage, he attacked any kind of formalism in criticism and, for this reason, his arguments with Clement Greenberg, the formalist critic of abstract expressionism, reached great dimensions. His aim was to bring forth the deepest concepts of art, its deepest meaning. He used to say that his support of Pop Art was based on the freedom it represented from the formalism of the previous expression. He was considered to be the thinker who changed the perception of the contemporary art critics' work.