Evive Health is a company that manages communication campaigns on behalf of health insurance plans and large employers. Using big data techniques and insights from behavioral economics, Evive deploys targeted and effective messages that improve individuals' health behaviors. This case follows Prashant Srivastava, Evive's Chief Operating Officer, and Jennifer Lindner, Evive's Creative Director, as they design a messaging strategy for promoting influenza vaccination at the free workplace clinics of a large utility company.