[eng] This thesis is concerned with the world wheat economy between 1939 and 2010, which may seem somewhat surprising for several reasons. First, the history of wheat is inextricably tied up with the evolution of world agriculture and, as is well-known, the relative importance of agriculture has declined significantly as a consequence of structural change. Second, we are particularly interested in studying the evolution of the international wheat trade, yet it is also well-known that there has been a substantial fall in the share of traditional bulk products, such as wheat, in the international agricultural and food trade over this period. Finally, it is well-documented that, regardless of location, there seems to be a “trading-up” consumption-adjustment pattern as consumers increase their income levels. This means that consumers all over the world tend to substitute high-value animal-protein-rich meat and dairy products for carbohydrate-rich grains such as wheat. Thus, it may seem untimely to write a thesis on something that, one may think, has become less important over time (and presumably will become even more insignificant in the future). There are, however, powerful reasons that justify the relevance of a thorough study of the world wheat economy. The thesis is composed of this introduction, three independent – although deeply interrelated – chapters, and a final summary section. The first chapter explores the major changes experienced in the world wheat market between 1939 and 2010. It looks at the evolution of wheat imports and exports in various groups of countries, identifies major trends, and offers a detailed explanation for those trends. The construction of a theoretical model serves as a vehicle for structuring the discussion: the wheat trade may be explained by looking at the supply and demand trends within those groups of countries, and particular consideration is given to institutional changes. The outlook for the world wheat economy immediately before the Second World War was decidedly gloomy. Trade and prices plummeted during the 1930s and a large number of interventionist measures were undertaken worldwide in order to deal with the so-called "wheat problem". However, the wheat trade today is almost ten times greater than it was in the immediate postwar years and the signs of market disintegration have disappeared. The aim of this chapter is twofold: first, it analyses the reasons behind the extraordinary expansion of the world wheat trade between 1939 and 2010, and second, it explores the main changes in the di6gstribution of wheat exchanges and offers an explanation of those transformations. Major patterns of change in wheat production and consumption in different groups of countries are identified, taking into account such institutional variables as national agricultural policies and their impact on wheat prices, the effect of international agreements, the influence of the international context, and the increasing influence of trading companies. The second chapter is specifically focused on one of the major trends in wheat trade identified in Chapter 1: the increasing concentration of wheat imports in a selected group of developing countries in which wheat consumption prior to World War II was virtually negligible. The growing wheat dependence of low-income countries has often been considered as problematic or even ‘non-desirable’ – as far as food security and economic development strategies are concerned – and it is for this reason that we opted to follow a ‘food regime’ approach. Food regime analysis is concerned with interpreting possibilities and conflicts inherent to the twenty-first century food system in historical terms. This chapter summarizes the theoretical discussion of the food regime method, and of the identification of different 'food regime periods' throughout modern history. While it is widely accepted that the so-called 'second food regime' has already ended, there is much discussion on whether, or not, it is possible to talk about a more recent, third food regime. This Chapter traces the evolution of the 'wheat complex' over the 'second food regime' (1947- 1973) and over the next 45 years, and offers an explanation for the evolution of world wheat trade distribution, based on food regime analysis. Certain authors have claimed that the collapse of the WTO Doha round of negotiations may be understood as a 'hangover' from the second food regime. Similarly, this Chapter argues that the increasing wheat dependence of poor and insecure countries over the last 40 years may be considered as a path-dependence outcome of a process initiated during the second food regime. Chapter 3 is also concerned with identifying the main drivers of the changing patterns in the composition of the world wheat trade. However, rather than analyzing aggregate wheat trade flows, it focuses on the bilateral structure of trade (from 1963 onwards). The estimation of several ‘gravity’ models serves to test the importance of variables such as distance, cultural proximity, and income growth. In contrast with Chapter 2, this is more focused on the ‘economic’ determinants of trade, and therefore pays less attention to the institutional framework in which the wheat trade occurs. However, an effort has been made to test the effect of regional trade agreements, and also that of the inclusion of the wheat trade under the World Trade Organization (WTO) agenda. The results are discussed and interpreted following a cliometric approach that takes into account the major findings of chapters 1 and 2.