This book provides a comprehensive conceptualization of perceived IT security risk in the Cloud Computing context that is based on six distinct risk dimensions grounded on a structured literature review, Q-sorting, expert interviews, and analysis of data collected from 356 organizations. Additionally, the effects of security risks on negative and positive attitudinal evaluations in IT executives' Cloud Computing adoption decisions are examined. The books second part presents a mathematical risk quantification framework that can be used to support the IT risk management process of Cloud Computing users. The results support the risk management processes of (potential) adopters, and enable providers to develop targeted strategies to mitigate risks perceived as crucial.