The structure of the agriculture sector in Australia appears to pose a fundamental constraint to 'product marketing' and 'value-adding' initiatives of the kind for which many are calling. A case is presented in this paper for the search for differentiation opportunities (as a rubric for product marketing and value-adding activity) to be regarded as a determinant of marketing system performance. This is related to firm-level contemplation of market levels, as distinct from segments within a level, to target. Criteria are presented for the identification of the appropriate market level for an organisation to target within a vertical marketing system and these are then analysed with a view to identifying appropriate grounds for policy intervention in such systems. It is argued that grounds can exist even in markets which are contestable and that agribusiness subsystems are common examples.