This paper investigates the questions of whether and how the evaluation of merit in academic disciplines changed between the early 1950s and the late 1960s. We analyze letters of recommendation written for prospective graduate students who applied to the Woodrow Wilson Fellowship Program during the periods 1951-1955 and 1967-1971, in the disciplines of economics, political science, philosophy, English and history. We find that in all disciplines, the relative use of intellectual and technical criteria increased during this time, the relative use of moral and social background criteria declined, while the use of personal criteria did not change. We find little evidence of disciplinary differences. In suggesting potential explanations for these findings, we focus on the impact of the dramatic growth and expanding diversity of academia during the postwar years.