We conducted a real-time qualitative study of the post-merger integration process between Nokia and Alcatel-Lucent in 2015-2023 to increase our understanding of the emotional dynamics of integration—which recent research has shown could be consequential to integration success. Our findings reveal prior research has undertheorized how organizational histories influence organization leaders’ and members’ appraisals and emotions during integration, emotions that influence subsequent cognition and action. Specifically, past integration experiences produce emotion-based narratives about integration, shaping organization members’ emotions toward integration in the unfolding present. We develop an analytically generalizable process model that elucidates how the present situation and organizational history jointly influence organization members’ appraisals and emotions, which in turn influence their integration behaviors. Our findings contribute to theory on post-merger integration and emotions in organizations.