The current study investigates with a multiple case study the relation between instrument design and policy success. The conclusion is that the instrument mix matters. The Flemish interventionist approach, which focuses more on traditional instruments, was not as effective as the Dutch stimulating approach, which uses a broad pallet of social and economic instruments, including many new environmental policy instruments. It is conspicuous that the government remains the most important regulator in all cases, although the importance of surrogate regulators is growing. Mostly the government is needed to stimulate or even create such surrogate regulators. Therefore, the government has a key position to decide which regulatory tasks will be transferred to surrogate regulators. This is currently restricted to capacity-building and certification.