This document is intended to provide an overview of the risk assessment field for managers and technical professionals in the Maritime and Offshore Oil and Gas industries. The risks addressed are primarily those affecting the safety of a vessel, facility or operation, but the methods discussed can also be applied to other types of risk. The concept of risk is defined, and the methods available to assess the risks associated with an operation are described. Guidelines for setting up and conducting successful risk studies are provided. Regulatory requirements that have prompted the development of modern risk assessment practices are described, and future regulatory trends are discussed. And finally, examples of risk assessment applications are discussed.