This book, for the first time, brings together and updates the groundbreaking work of renowned risk theorist and researcher Ortwin Renn, integrating the major disciplinary concepts of risk in the social, engineering and natural sciences. The book opens with the context of risk handling before flowing through the core topics of assessment, evaluation, perception, management and communication, culminating in a look at the transition from risk management to risk governance and a glimpse at a new understanding of risk in (post)modern societies.