Since its creation in 1966, the Asian Development Bank (ADB) has grown up to a point that many today hesitate to consider it as a regional bank, ranking it instead in the major league along with institutions such as the World Bank. It is true that the ADB has always mobilized the world’s richest countries in order to invest in Asia’s economy and human capital. And it is also true that its Asian and Pacific developing members (which excludes Australia, New Zealand and Japan) have progressed to such an extent that their share of the world GDP has more than tripled from 8% in 1966 to 25% in 2015. Many of these countries, like South Korea, India and China, have become leading players in the world economy. Such a growth gave more prestige and influence to the ADB worldwide. And yet, as we will see in the following pages, the ADB has frequently been described as a bank under the control of two countries, Japan and the United States. According to some scholars, the Bank has served these countries’ hegemonic interest over Asia, and consequently reduced its role to a mere tool for international powers to implement capitalism in the region. On the other hand, other analysts draw a different picture, presenting instead a Bank with a globalizing agenda but being forced in the long run to adopt regionalist policies to reach its developmental objectives. The present chapter doesn’t pretend to bring the final word on these issues. It chooses instead to make a global survey of ADB’s evolution since its beginning, showing its growing complexity both as a fund gatherer and as a developer of regional economies. After presenting its origins and its mandate, it will describe the Bank’s membership, its organization and its activities as a borrower and as a lender of capital. There is no doubt that the economic conjuncture helped ADB to grow the way it did. The 1973 oil crisis was the first event justifying an increase in capital and in borrowings. The Asian crisis of 1997-98 and the 2008 meltdown incited the Bank to reach new financial plateaux. These crises weren’t obstacles but an opportunity to jump higher. Nevertheless, other factors also played in ADB’s evolution. Firstly, the strong presence of Japan within the Bank not only as a shareholder, but more so as the biggest lender of funds. Let’s not forget the fact that the Bank’s presidents have always been Japanese and most of them worked for Japan’s Ministry of finance. To be sure, the presence of the United States limited Japan’s ambitions over the Bank, as some scholars mentioned it. However, as others advanced it, the ADB’s policy of ‘open regionalism’ (as characterized by the ‘growth triangles’) remains a contribution of Japan over the American policy of giving priority to the private sector. Secondly, the remarkable development of many Asiatic countries forced ADB to grow well beyond its initial expectations. All of them being members of ADB, they made a point to push forward their influence within the Bank. A country like South Korea increased its voting power as well as its financial contributions as money lender. Nations like India and China have become such major borrowers that ADB, after 2010, had no choice but to increase its financial capacities to a level never reached so far. And thirdly, ADB is part of bigger family, comprising international institutions like the UN, but also other development banks, regional or non-regional. An examination of the managing personnel shows how these institutions share their managerial personnel. This common influence, although not studied here, is real and many policies the Bank adopted were in conformity with what was prevailing in other RDBs. As a regional development bank, has ADB lost its usefulness? In his introductory chapter, Peter McCawley presents a figure comparing ADB’s financial operations with developing Asia’s GDP (PRC excluded). The figure shows that the Bank’s operations oscillated from 0.5 to 0.8% of the GDP, and after 2000, this percentage declined even more because of the exponential growth of Asia’s economy. It is only after 2013 that the Bank’s operations could reach 0.5% again. Such a low percentage may look as a modest contribution throughout the Bank’s history. However, the ADB’s influence in underrepresented by this statistical comparison. The Bank represents one of the surest source of information about Asian economy and society. Moreover, its resident missions did contribute to create a growth model for the entire continent. This way, like the other RDBs, ADB has been (and still is) a useful tool to link micro-economy to macro-economy. Through its borrowings and its co-financing operations, the Bank has contacted an enormous number of financial and economic institutions throughout the world and has been influential enough to make them accept its macro-economic vision. And the Bank intends to play this role again in the future.