We propose a new multivariate estimation of the WS-PS model on French macroeconomic data. Starting from a theoretical presentation of structural determi- nants of wage and price setting, we have estimated using a conditional VAR-ECM model, the relationships between unemployment rate, real labour cost and its deter- minants over the 1970-1/1996-4 period. The estimation leads to a rate of equili- brium unemployment nearing its effective level at the end of the period. The rise in equilibrium unemployment, by 10 points in 25 years, would be accounted for essen- tially by the rise of tax and social deductions, the slow down of labour productivity and by deterioration of job security assessed by the downsizing rate. The terms of exchange which have essentially varied under the impact of oil crises and distortion between proposed and required qualifications on labour market, would only account for a slight part of the rise of equilibrium unemployment. This study moreo- ver leads to questioning the influence of numerous other determinants : the lesser digressiveness of social deductions wouldn't have had any impact on the increase of equilibrium unemployment and it would be the same for replacement rate, wor- king hour reduction, the Smic increase and the real interest rates (which wouldn't have had a direct impact except their effects on labour productivity).