This paper presents a method for assessing the user cost of capital which uses firm-level accounting data for French companies. The method relies on a modelling technique which takes into account the financing structure, the bank interest rate and the tax burden on firms and shareholders. The resulting analysis of the changing cost of capital shows firstly the wide range of stated interest rates paid by companies to finance their debt burden. The changes in the user cost of capital in the last two decades reflect the changing cost of equity capital. The cost of equity capital falls because of the constant fall in risk-free investment income, but also because of the marked reduction in taxes on profits. The methodology chosen includes neither risk premiums nor premiums on securities (issued for futures market transactions). The effect of including these two components may be to alter the cost of capital, or perhaps even changes in it. Over the period 1984-2002, the average cost of capital calculated using this method fell by six percentage points. Only changes in the share premium on this scale are therefore liable to undermine this average fall in the cost of capital.