This chapter discusses sugarcane workers’ engagements with Nicaragua’s national social security system. Social security systems may seem less “open” than legal or regulatory or irrigation systems, but historical evidence about the place of sugar production in the development of the Nicaraguan welfare state shows how conditions like CKDnt challenge the structural integrity of social safety nets. Social security systems are premised on the idea that to receive insurance from the state, one must be identifiable as a productive worker. Since social security provides aid to injured workers, such systems also depend on an ability to clearly define what counts as a workplace injury. What the CKDnt epidemic has exposed is that the categories of worker, and of the working environment, turn out to be fluid and contestable. The chapter uncovers the messy negotiations that go into establishing which bodily and ecological conditions count as “working conditions.”