Obtaining the support of affected stakeholders is a crucial first step to successful implementation of any public policy, including flood mitigation policies. Public support for flood mitigation policies is largely influenced by flood risk perceptions and flood risk perceptions are, in turn, shaped by a multitude of factors. This paper explores the impact of the determinants of risk perception on willingness to pay for flood risk prevention in Dunkerque (France) using a contingent valuation survey. We find that whether or not respondents include their home within their perceived flood risk areas, trust in flood mitigation measures, environmental beliefs and socio-economic factors are strong predictors of public support for flood risk prevention, whereas actual distance of a respondent’s home to the flood source, knowledge of flood risk, prior experience and trust in local authorities have a limited influence. Policy implications and suggestions for future research are discussed.