Despite the vast scholarship on the Ku Klux Klan during Reconstruction, the movement's pattern of participation has received sparse attention. This study uses modern, digitized historical records along with older sources to re-evaluate the author's earlier study of Klan membership in Alabama. The most common profile for a Klan member in Alabama was the son of a middling slaveholder, for whom Emancipation had led to a catastrophic loss of wealth and standing. The emergence of widespread terrorism came about when a broad social constituency, the restive sons of middling slaveholders, linked up with the displaced political establishment.