The ongoing negotiations of the World Trade Organization (WTO) on agriculture has triggered an increased interest in the linkages between commodity production and public goods in agriculture. This paper takes a closer look at this issue. Particular emphasis is placed on production economics and policy design issues. Production is placed in a multi-product multi-input setting. The provision of public goods from agriculture is analyzed utilizing a principle-agent framework. Particular emphasis is placed on issues pertaining to incentive compatibility, informational aspects and the participation constraint. Public finance aspects of various policies are also addressed. Price supports are of particular interest as they are widely used in European agriculture. This makes analyses of price supports particularly relevant.