The present paper seeks to locate the Bhaduri-Marglin (B-M) model as an historical outcome of the Left's internal disputes over the prospects for social democracy. In better contextualizing the B-M model as a historical response to the perceived political economic failings of the social compromises upon which the growth of post-War advanced capitalist economies had rested, both the model’s popularity and its potential limitations can more easily be understood. Though the B-M framework has frequently come to be referred to as the neo- or post-Kaleckian growth model, such labels perhaps obscure the model's diverse ancestry. The model constituted an attempt to reconcile seemingly incompatible theoretical perspectives, and to highlight those special conditions that made possible a ‘Golden Age’ of social democracy. Moreover, they sought to show that the conclusions of Keynesian social democrats and of radical Marxists could be viewed as two possible outcomes of the same broadly Keynesian theoretical framework in which investment played a leading role. While this synthesis has fostered a vast literature and useful dialogue, it is argued that it should, nevertheless, be seen as the outcome of a generation Left social scientists that had become deeply skeptical of the possibility of egalitarian redistribution under capitalism, and of the political ambitions of Keynesian and social democratic parties.