Fixed statutes and regulations often have variable consequences over time. If left unattended, such drift can severely erode the performance of government as an institution of representation. To better understand the mechanics of policy-making in a changing world, we develop a positive theory that captures political drift in a dynamic separation-of-powers system. We show analytically that a distinctive combination of legislative supermajoritarianism and agency discretion—institutional features that, in isolation, elicit widespread criticism—can effectively ameliorate policies’ susceptibility to the vicissitudes of exogenous change. The critical mechanism for governmental accommodation of drift is delegation, which increases all decision makers’ well-being by reducing fluctuations in outcomes. Although the complete smoothing of outcomes is attainable in a separation-of- powers system, we show that this is typically not achieved in equilibrium. The presence of drift provides an opportunity for self-interested legislators to extract a distributional benefit from their fellow legislators at the expense of overall policymaking efficiency.