This chapter explains risk management, focusing on risk prevention as well as mitigation. Risks and opportunities occur as a result of an action, a decision or something totally unexpected happening. The traditional approach of summing up the risk and the severity of an event is to multiply the probability by the severity and show the results in a matrix known as a risk rectangle. In the traditional management paradigm, risk management is treated as, and documented as, separate management and engineering processes. When risks are identified in work packages during the project planning state, a decision has to be made as to prevent or mitigate the risk. National Aeronautics and Space Administration (NASA) and the US Department of Defense have many projects dependent on technology that is still being developed. NASA developed the technology readiness level to minimize the risk of the technology not being available when needed.