In previous chapters our discussion has been confined to Kalecki’s analysis of a closed economy. The aim of this chapter is to show how he included the effects of foreign trade in his approach to effective demand. Maybe not everybody, not even Kalecki’s most unconditional admirers, would entirely subscribe to Joan Robinson’s assertion: “Keynes’s General Theory was worked out in terms of a closed system. … Here also Kalecki’s work claims priority” (Robinson, Preface to Kalecki (1969)). But we claim that Kalecki had a very original and novel approach to analyse open economy macroeconomics. Of course, some of the points he raised are now of common knowledge. However, we submit that in any case this part of his theory is still worth studying because, as is usually the case with this author, one can always find something which is unique and appealing in his reasoning.