Why are some countries are rich and others poor? To help answer this question, we examine leading theories of economic development. In light of these theories, we then examine the development experiences of three major regions of the world. We next consider a series of issues about development, including the effects of ethnic diversity, corruption, natural resources and women’s empowerment on economic development. We conclude with an examination of the effects of the international interactions—via trade, foreign aid, migration and war—on economic development.