While many crop insurance systems have been reformed around the world, few academic researches have addressed the determinants of the decision on crop insurance at the farm's micro level. In this article, both the financial and the agricultural literature lead to the identification of many rationales for the crop insurance decision. Using data from the period 2003-2006 on a representative survey of French farms (FADN-RICA), we investigate the different factors that incite farmers to insure against crop risk. We emphasize that the highest risk farms are more likely to have insurance and this decision is positively related to the past amount of claims. Insurance is subscribed by larger farms because insurance appears too expensive for smaller farms, which are indeed naturally less diversified. Interestingly, financial variables (such as capital structure or return on investment) do not significantly determine the insurance decision.