One of the eternal challenges of economic development is how to identify the economic activities that a country, city, or region should target. During recent years, a large body of research has shown that countries, regions, and cities, are more likely to enter economic activities that are related to the ones they already have. For instance, a region specialized in the exports of frozen fish and crustaceans can more easily start exporting fresh fish than heavy machinery. This research has illuminated a new chapter in the economic development literature, but also, it has left an important question unanswered: what is the right strategy for countries wanting to diversify their economy?