This paper surveys and considers in perspective the correspondence between Roy Harrod and Dennis Robertson. 194 letters and notes are extant, dated from 1926 to 1960, discussing a wide range of topics. Economic dynamics, growth and cycles are debated at length with reference both to Harrod's and Robertson's writings and to the developments taking place in the field. But other subjects often recur, in particular international trade, imperfect competition, monetary theory, and especially the relationship with Keynes and Keynes's economics.