This dissertation comprises four essays investigating the impact of bank governance structures on performance, risk, and stability. The first three studies analyze financial expertise of supervisory board members as a governance instrument: The first study focuses on the extent to which supervisory board members may be regarded as financially literate. The second study places emphasis on the impact of expertise on performance, risk, and stability at German savings banks, while the third study comprises the comparison of the mentioned impact at savings and cooperative banks. Finally, the fourth study analyzes the impact of ownership concentration on banks' performance, risk, and stability on a global level.