This article builds a developmental model of probation evolution based on the dynamics generated by its feedback effects, illustrating its claims through a case study of Chile's recent probation politics. The article posits that probation emerges out of the negative infrastructural and political feedback effects of the prison. As probation generalises, it creates its own growing negative political feedback. In time, the field can enter a state that we label the politics of probation, providing for substantial political conflict and fluctuance. The article shows how different actors mediate in the conflict around the politics of probation.