This book investigates the determinants of bank capital structure and procyclical behavior of leverage. A panel data analysis is developed to find out the relation between different types of leverage ratios and asset growth of banks. Furthermore, possible impacts of bank specific and macroeconomic variables on the bank capital structure are discussed. The book concludes that the leverage of Turkish banks is procyclical, which is the outcome of a positive relation between asset growth and leverage. The procyclical leverage could contribute to higher instability in the financial sector and the overall economy. Therefore, further regulations are assumed to be necessary. Size, profit, number of banks, inflation, exchange rate, and gross domestic product are the factors that affect Turkish banks' capital structure.