This book is focused on the factors affecting our decisional processes. Regret and disappointment are the two crucial emotions involved in decision-making as they affect our choices. Whereas regret is related to a comparison between outcomes of different choice alternatives, disappointment is seen as a comparison between the outcome and the expectations of a chosen option. They are also differently related to the responsibility on the decision: regret is related to self-agency and personal control; disappointment is related to other-agency and to external control. The experiments presented here were then aimed at investigating the factors that determine the experience of regret and disappointment and how they affect choices. Although emotions are sometimes hard to measure and difficult to observe, recent developments in emotion research give us the tools to understand the factors affecting decision-making. Therefore, findings from studies reported in this book suggest new and promising knowledge in this field of research.