Tadeusz Kowalik is inevitably associated with the work and ideas of his early mentor Oskar Lange, and his collaborator, after Lange’s death in 1965, Michał Kalecki. In large part this association is due to the central role played by Kowalik in the editing of the two senior economists’ collected works. To a great extent this association is viewed uncritically, and rests on a conflation of the theories of the two senior economists. Although both had a broadly socialist approach to politics and economic analysis, Lange and Kalecki differed fundamentally in their respective interpretations of Marxist political economy, the Keynesian Revolution, and the prospects for socialism. Kowalik overcame this contradiction by pointing to their shared ideals, by the honesty of his interpretation. But his major research on Rosa Luxemburg reveals a shift towards Kalecki.