This paper shows that although the crisis triggered more openness towards fiscal policy activism at the Fund, it nevertheless did not lead to a paradigm shift. Specifically, it argues that IMF research engaged in a debate within mainstream New Consensus macroeconomics over the merits of expansionary fiscal consolidation in a way that largely supported some New Keynesian skepticism that austerity can be expansionary in a recession. This opening was facilitated by an emerging epistemic coalition between Berkeley academics and IMF economists based in the influential Fiscal Affairs Department and the Chief Economist Office. Their epistemic struggle was carried out largely on the methodological terrain, with new databases and ways of calculating the fiscal multipliers taking precedence over theoretical debates. Nevertheless, new ideas entered the IMF research agenda: the problems posed for the Ricardian Equivalence Thesis by persistently high unemployment, the potentially self-defeating effects of austerity on debt and deficits, and the relevance of poverty and inequality issues for future growth. To make these arguments, IMF economists were careful to frame their message in a way that resonated with the Fund’s scientific culture, and were keen to graft and layer their findings upon some of the broad New Consensus macroeconomics tenets. Rather than be limited to IMF researchers, many of these findings were gradually adopted in the IMF’s public policy pronouncements, an outcome facilitated by the fact that some of their proponents were researchers who occupied prominent positions in the Fund’s policy-making institutions.