In many countries, policy-makers lack relevant information to guide the design of innovation strategies and policies that will help developing innovation capacities and triggering agricultural innovation processes. Existing assessment methodologies of agricultural innovation systems consist mainly in taking stock of a current situation based on an external evaluation made by experts and are not embedded into policy dialogue, planning and decision processes. In order to design an action-oriented AIS assessment for informing policy makers, a Delphi consensus study has been conducted. The objective was to gather data from experts in agricultural innovation within their domain of expertise (scientists, development workers, policy makers, farmers' representatives, entrepreneurs) so that to achieve a convergence of opinion on the way to conduct an action-oriented AIS assessment for supporting policy makers. A consensus could not be found in all aspects. Experts reached agreement on principles for the assessment process and methodological principles for collecting and analysing data sets. Basic questions were controversially discussed about the purpose of the assessment (supporting dynamics or maximizing effectiveness of the innovation system), the use of high-level indicators (are they really useful for AIS stakeholders?) and the domains to be considered for understanding processes (research and education, bridging institution, firms and farms, environment and policies) and identifying leverage for action (focus on the structures, functions, capacities or interactions within an AIS?). Adaptations to the Delphi approach are discussed and improvements are proposed regarding the selection criteria of experts, the organization of the workshop and the number of rounds.