Born in Minnigaff, Kirkcudbrightshire, Mirrlees was educated at the University of Edinburgh (MA in Mathematics and Natural Philosophy in 1957) and Trinity College, Cambridge (Mathematical Tripos and PhD in 1963 with thesis title Optimum Planning for a Dynamic Economy, supervised by Richard Stone). He was a very active student debater. One contemporary, Quentin Skinner, has suggested that Mirrlees was a member of the Cambridge Apostles along with fellow Nobel Laureate Amartya Sen during the period.