The Paris agenda on aid effectivess emphasises support for recipient-owned development strategies, increased use of national systems and more co-ordinated and predictable donor actions. Monitorable targets for such behaviour have been agreed, but the connections with expected development benefits are as yet unproven. Alternative views of the rationale for aid agencies, transaction costs and conditionality, in which there is rarely complete preference alignment and trust between donors and recipients, introduce further complications. Four additional policy measures are identified which cannot be managed easily within the Paris agenda: better international balancing of aid allocations; new instruments with longer commitment horizons; liquidity arrangements to enable 'scaling up' across several countries; and independent aid rating institutions linked to market-like sanctions.