A visionary in political polling, the late Patrick Caddell revolutionized the way campaigns use data to understand voters. Best known for his role as pollster and advisor to President Jimmy Carter, Caddell was instrumental in developing a populist messaging strategy that energized disaffected voters. He launched his career while still at Harvard, later advising more than 150 campaigns and shaping the field of opinion research for decades. Despite a later pivot across party lines, Caddell’s early work on behalf of Democratic leaders and his influence on generations of political consultants earn him a place among the greats.