This book presents the state-of-the-art in non-linear dynamics and sunspots. These two topics have been the core of an international conference on instability and public policies in a globalized world, organized at Aix-Marseille School of Economics and GREQAM in honor of Jean-Michel Grandmont. He has made significant contributions on general equilibrium theory, monetary theory, learning, aggregation, non-linear dynamics and sunspots. This book assembles contributions by Jean-Michel Grandmont's colleagues, students and friends that have been influenced by his works and that are at the frontier of research in this domain today.