Letters consist of responses to queries and questionnaires that Barbara Rose and Irving Sandler sent to contemporary artists as research for writing projects. Questionnaires were sent in preparation for an article entitled "Sensibility of the Sixties," which appeared in the Junuary-February 1967 issue in
Art in America
, and responses were received from Robert Motherwell, Robert Craig Kauffman, Len Lye, Robert Morris, George Segal, David Hare, and others. A separate query asked sculptors for their assessment of contemporary sculptor's needs and the potential for patronage. Respondants to this query include Carl Andre, Robert Morris, Charles Frazier, Robert Craig Kauffman, Robert Murray, Anthony Padovano, Ron Bladen, Roy Lichtenstein, Len Lye, Sol LeWitt, Heinz Mack, Otto Peine, Dan Flavin, and Donald Judd.