Despite variety, plurality and complexity, analysis of (inter) organisational arrangements in the mixed economy of unitary states is still dominated by the centralistic frame of reference suggested by the formal-legal characteristics of these systems. Despite a growing sense of discomfort with this situation, and a growing critique of the unwarrantability of assumptions of uniformity and centralised control, an alternative theoretical approach does not yet seem to have been developed. This article explores the field of public administration in order to see what perspectives can be offered to the analysis of plural public structures. It distinguishes between a policy-instrumental and a political perspective. Differences are outlined in confronting these perspectives with respect to some analytical and normative issues to be resolved.