Do investors prefer the stocks of firms that exhibit a high degree of CSR? The bulk of empirical studies use market data to assess the financial value of CSR and are not able to disentangle the financial and ethical effects of corporate social responsibility on firm value. Based on an experimental design, we show that subjects asked to assess stocks tend to overvalue, by one-third on average, the stock of a company with an AAA CSR rating compared to when they do not have access to this information. We controlled for the fact that the increase in fundamental value is the consequence of a purely ethical behavior and not a disguised financial one. Furthermore, a poor CSR rating does not seem to be penalized.