How the Party selects, educates, appoints, trains, monitors, evaluates, retrains, promotes, and, when necessary, demotes, its cades and officials. This is the purview of the Organization Department of the CPC Central Committee, which has long operated outside the glare of the media or public discourse. We explore how the Party's personnel system actually works — the down-to-earth practice at the Party's governance grassroots, and the policy-setting theory at the Party's central intellectual brain trust. We focus on the Party secretaries of China's nearly 3,000 county-level administrative regions, the public sector CEOs of their regions. What do these county Party secretaries actually do? What do they need to learn and how do they learn it? While all political systems have tradeoffs, to discern how the Party works at 100, discern how the Party's personnel system works...