A new data set shows the evolution of capital ratios for the United States, the United Kingdom, Switzerland, and Germany. The chapter questions the accuracy of capital/assets ratios and argues that cross-country comparisons of capital ratios are of little explanatory value without a historical narrative. Firstly, the capital/assets ratios used by the academic literature usually consider paid-up capital and disclosed reserves only. However, the total liability of shareholders can go beyond the paid-up capital (double or unlimited liability), which influences the level of capital/assets ratios. Secondly, accounting standards allowed the extensive build-up of hidden reserves in the United Kingdom and Switzerland. The chapter shows that the capital strength of banks, considering hidden reserves and shareholder liabilities, is underestimated. Existing publications comparing capital/assets ratios on an international level neglect such issues. Additionally, the chapter analyses structural changes in the assets of British, Swiss, and US banks using the Basel I framework of 1988 for a historical simulation.