Vulnerability assessments of coastlines are often done using financial criteria (Carter, 1999). Thus, resources threatened by coastal retreat and whose use is non-profitable are rarely included in impact statements. Little-known archaeological sites are examples of such resources. This study aims at integrating the presence of such sites into coastal vulnerability analyses. This study focuses on two areas located in the Morbihan department in France: Suscinio Bay and the Pénestin Cliffs. For each site, the vulnerability is mapped twice using a semi-quantitative method. During the second mapping exercise, the risk of archaeological heritage loss is included in the analysis. Comparing the different results obtained highlights the fact that introducing this new parameter leads to an increase in coastal vulnerability. These relatively simple findings echo more complex discussions. They put into question the theoretical basis of the analysis by underlining its subjectivity as well as subjectivity's corollary: uncertainty. Both of these characteristics appear related to the researcher's attitude towards the models developed by social science. Such models determine the value system through which the threat of destruction to archaeological objects is assessed, and hence the valuation method developed in order to measure their vulnerability.