Book excerpt: Does competition spur productivity? And if so, how? These have long been regarded as central questions in economics. The extent of competition can be influenced by policy decisions, so understanding how competition impacts productivity and, in turn, living standards is of more than academic importance. To fully answer these questions of whether, and how, an increase in competition impacts productivity, two issues must be addressed. First, the authors define what we mean by an ¿increase in competition.¿ Second, they attempt to understand the mechanisms through which competition impacts productivity. Both issues present substantial challenges, which the authors address. Illustrations. This is a print-on-demand publication; it is not an original.