The management of the coastal water control system in the medieval Low Countries was characterized by a bottom-up organisation, with apparently broad participation of all people concerned. The joint effort of rural communities facing the threat of inundation and land-loss, is often considered to have been at the very origin of a long-lasting tradition of non-hierarchical, bottom-up decisionmaking – the so-called ‘polder-model’. This hypothesis is verified for the latemedieval Flemish coastal plain. Notwithstanding the formal attention paid to participation and broad consultation, the everyday practice of decision-making in rural water management was probably more influenced by hierarchical relations and income strategies of elite social groups than often thought, with the participation of peasant populations even further limited as the commercialisation of the rural economy went on.