This study measures the magnitude of transaction costs incurred by milk producers in their contractual relations with dairy processors in two different coordination mechanisms: centralized contracting through a marketing board and decentralized bilateral contracting. Interviews and surveys were conducted to estimate transaction costs faced by producers marketing through the Québec milk marketing board in Canada and bilateral contracts in England and Wales in the United Kingdom using the measurement methodology of the cost of exchange. Our results show that the relative magnitude of transaction costs incurred by producers across both settings is quite low, which indicates that both hybrid coordination mechanisms minimize transaction costs in the dairy sector. However, results from the bilateral contracting setting indicate a strong heterogeneity of transaction costs levels among farmers. In that respect, the milk marketing board and its institutional setting would act as a collective insurance, pooling transaction costs and sharing them among producers. Our analysis leads to recommendations on bilateral contracting.