This study examined lay theories about the relationship between biomedicalization and the exclusion of depressed people. More precisely, lay theories were examined under the two dominant models which predict that attribution of mental illness to biomedical causes should reduce perceived responsibility and either decrease (attribution theory) or increase (medical model) perceived exclusion of depressed people. The goal was also to assess the impact of three factors most often disregarded from both models, namely, type of responsibility (mental state vs. behaviors), life domain (family vs. occupational environment) and familiarity (contact vs. personal experience). Analysis of data from a representative survey conducted in the Nord Pas de Calais French region (n = 12,533) showed that contact and personal experience have opposite effects on perceived exclusion and that lay theories differed as a function of type of responsibility. The role of ascribed responsibility for behaviors did not depend on life domain and was consistent with the medical model. On the contrary, the role of responsibility for mental state was limited to exclusion from family and in line with attribution theory. Future research should examine more thoroughly the role of the different kinds of biomedical explanations in relation with both types of responsibility.