Chiefs of staff in the modern presidency usually assume three major roles during their tenure: administrator, adviser, and guardian. Through original survey data, this article explores these roles by examining six chiefs of staff who served during the Reagan-Bush era: James Baker, Donald Regan, Howard Baker, Kenneth Duberstein, John Sununu, and Samuel Skinner. Based on the evidence, Howard Baker and James Baker were perceived as the most effective chiefs of staff in performing these three major functions. Not surprisingly, the Reagan administration prospered during both Bakers’tenures.