This survey paper explores the literature on decoupling of farm programs that has emerged in the last 10 years. The paper identifies and assesses the various channels of potential coupling of decoupled farm payments and provides a taxonomy of coupling mechanisms found in theoretical and empirical papers. Coupling of decoupled payments is pervasive but effects when measurable are small, with the exception of the impact on land values. The paper points to unresolved issues on potential coupling mechanisms for further research.