The concept of risk has been central to the theory and practice of finance since Markowitz’s influential work nearly 60 years ago. Yet, risk management has only emerged as a field of independent study in the past 15 years. Advances in the science of risk measurement have been a main contributor to this remarkable development as new risk measures have been proposed and their properties studied. These measures, which in the past have only applied to market risk, are now being applied to credit, operational, and liquidity risk as well as to portfolio optimization. A growing emphasis on risk budgeting has also sparked a quest for an integrated risk measurement framework. But risk management is more than the application of quantitative techniques. A long list of past financial disasters demonstrates that a profound and concrete understanding of the nature of risk is required and that adequate internal controls are crucial.