Nothing exists or persists without work. Whether the event is a physical object, a social institution, a political order, a human right, or an ecological condition, some system must be performing work to produce or sustain it. Work is therefore the most important analytical category within STF because it directs attention to the actual processes responsible for creating and maintaining reality. If an outcome exists, the systems thinker must ask: What work is being performed, by whom or what, and through which system?