This book hopes to unveil some of the internal dynamics of global health, in light of two major recent crises: the A(H1N1) pandemic between 2009 and 2010 and the 2014 Ebola epidemic. Our hope is that readers of this volume will discover analytical frames and plural accounts doing justice to some of the various levels at which managing global epidemics is done today. The two very different crises are somehow from opposite ends of the epidemiological and preparedness spectrum, as we will demonstrate. This polarity allows us to examine the Global Health System in two contrasting modes of functioning: a well-prepared- for epidemic versus an unexpected outbreak – albeit, ruthless surprises, varied controversies and similar difficulties in contextualizing chosen public health interventions lie at the core of both responses.