Whereas for a long time Europe and its off-shots dominated worldwide economic growth, more recently East Asia, followed by South-East Asia, China, India and Brazil, among others, have experienced the highest rates of economic growth. However other parts of the world still lag behind or show at least not more than modest signs of growth. This lecture will reflect on the history of long run growth, discuss alternative theories that try to provide explanations for the contrasting dynamics and examine empirical research testing the validity of the various approaches. The resulting policy implications are debated in depth. Particular topics that are discussed in this context are the role of geography versus institutions, the relevance of poverty traps, the role of trade openness as well as the effectiveness of development aid.