1. Introduction

This chapter provides a detailed overview of the relevant concepts and theories that this book builds on. The increasing interest in the soft side of business has been found to have influenced the emergence of emotion research in organizations. Based on cognitive appraisal theory, emotions are short-term reactions to events in our surroundings that we believe to be personally relevant. At work, affective events theory suggests such emotions arise from interpersonal or task-related incidents and that they modify behaviour. Change periods, such as post-acquisition integration, are very likely to trigger emotions. However, whereas previous acquisition research has focused on negative emotional states, this book builds on emerging discoveries of how positive emotions can ease change.