Recent discussion of the process of policy reform has tended to focus on public and private interest theories of public choice as alternative models. The analysis of Australian agricultural policy presented in this paper draws on several extensions of the private interest model including the contractarian framework, extra-rational considerations such as moral attitudes and the desire to participate. Recent agricultural policy reforms in Australia are examined in the light of those theories. This examination highlights the importance of ideas and changes in the rules for policy formulation in influencing policy outcomes. In some cases the private interest theory appears to offer an adequate explanation while, in others, it provides only a partial explanation of policy change, and requires extension if policy choice is to be influenced, or even understood. An important independent role for economists and policy makers is seen both in the formulation of policies and in the design of rules for policy choice.