["Oxford Bulletin of Economics and Statistics, Volume 88, Issue 2, Page 367-374, April 2026. ", "\nABSTRACT\nThis article investigates the structural interpretation of the marginal policy effect (MPE) within nonseparable models. We demonstrate that, for a smooth functional of the outcome distribution, the MPE equals its functional derivative evaluated at the outcome‐conditioned weighted average structural derivative. This equivalence is definitional rather than identification‐based. Building on this theoretical result, we propose an alternative identification strategy for the MPE that complements existing methods.\n"]