Although IS studies have begun to recognize the role of emotion in decision making, the research in this area is still in its infancy. The exploration of IS decision making phenomena through the lens of regret can offer rich implications to both research and practice. The presence of regret, for instance, can explain how and why IS decision makers choose a certain option. Motivated by the gap in the literature, the three papers in this dissertation investigate the role of regret in decision making in IS contexts. Specifically, the three projects investigate the following: IT real options decision in the context of RFID investment in libraries, whistle-blowing decision in the context of violations of heath information privacy, and process documentation decision in the context of investment in process improvement initiatives in an IT project. The contributions and implications of the three studies are presented further.