DZ BANK is the leading institution of the cooperative banks in Germany and is one of the most important credit institutions in the country. Its history is largely unknown to the general public. An international team of economic historians now presents the first comprehensive account. The roots of DZ BANK lie in the cooperative central banking system of the 19th century, particularly in the Prussian Central Cooperative Bank founded in 1895. Since their inception, cooperative financial institutions have played a significant role in providing credit to various sectors of the economy and have been instrumental in shaping the stability factor of the "middle class" in Germany. However, the history of credit cooperatives has received little attention from economic historical research so far. This also applies to the role of the credit cooperative system.