We have employed a simple model to analyse market regulation in a situation with multifunctional agricultural production, i.e., a public good produced jointly with a private good, and where there is imperfect competition in processing. We have analysed the impact on welfare of two archetype regulatory institutions formed to overcome the market imperfections. The institutions, a Regulatory Marketing Board and a Regulatory Marketing Cooperative, are both represented in the Norwegian agricultural market. Taking into account the cost of public funds, we find that the Board in general ensures the highest social welfare. The Cooperative does not replicate the Board solution unless restricted by a price cap and in combination with a production subsidy. If the restricted Cooperative is able to practise a higher degree of cost sharing than the Board, it may however produce the highest welfare.