Two widely heralded yet contested approaches to economics have emerged in recent years. One follows an older, rather neglected approach which emphasizes evolutionary theory in terms of individuals and institutions. The other emphasizes economies as complex adaptive systems. Important concepts from evolutionary theory include the distinction between proximate and ultimate causation, multilevel selection, cultural change as an evolutionary process, and human psychology as a product of gene–culture coevolution. Relevant concepts from complexity theory include self-organization, fractals, chaos, sensitive dependence, basins of attraction, and path dependence. This book explores these two bodies of theory and their potential impact on economics. Central themes include the challenges that emerge through integration, evolutionary behavioral economics, and the evolution of institutions. Practical applications are provided and avenues for future research highlighted.