Almost immediately after the publication of Keynes’ major work, there were the first attempts to test the Keynesian consumption function and its theoretical implications. This chapter starts with an examination of the background of the empirical work relating to the Keynesian consumption function. One major finding was the difference between the long-run and the short-run behaviour of the consumers’ consumption patterns, known as the ‘Kuznets’ Paradox’. It will thus proceed with Simon Kuznets’ empirical work on consumption, which set the basis for the emergence of alternative consumption functions to the Keynesian formulation. The chapter will finish with a critical discussion of the early empirical dimensions of the paradox, also focusing on subsequent interpretations of its econometric methodology.