A vast amount of research has been carried out to help us understand the main factors influencing mergers and acquisitions (M&A) performance. Although the existing body of knowledge focuses mainly on macro-level factors, there is an increasing interest from scholars and practitioners in understanding the micro-foundational factors occurring at individual and team levels. This chapter focuses on the importance of emotions – a central facet in individual reactions to workplace events – in M&A processes. To this end, the authors carried out a multi-phased search for articles on micro-foundations in M&A settings published by Business and Management (B/M) and Organizational Behavior and Psychology (O/P) journals. The authors reviewed 41 papers and used the circumplex model to identify and categorize 19 themes related to individual emotions involved in M&A processes in terms of positive/negative valence and high/low activation. The findings show that scholars mainly assume a risk mitigation perspective and focus on themes related to change resistance (negative emotions with high activation) by providing prescriptions on how negative emotions could be mitigated to avoid eroding acquisition performance. Hence, the authors suggest that (a) there should be more efforts to integrate different streams of literature, namely between the strategic and operational/behavioral areas of knowledge and (b) future research should focus on understanding how positive emotions like change proactivity (positive emotions with high activation) might be essential to enhance acquisition performance.