The measurement of the economic resource of voluntary work for an organisation, generally an association, should be encouraged by the prospect of building a satellite account of non-profit institutions. It is nevertheless a tricky operation which, due to its inherent uncertainties, gains from being based on surveys of the bodies for which volunteers work and the individuals themselves. The first step is to quantify voluntary work with a unit of time. Use of INSEE's October 2002 Vie Associative (Civil Society) survey of households provides an estimate of this resource at 820,000 «full-time equivalent» jobs in mainland France. Sport, leisure and culture alone account for nearly half of these. Many economists, and also civil society players themselves, are reluctant about putting a monetary value to this given time. Such a valuation also faces many theoretical and empirical problems. The estimates obtained based on the Vie Associative survey and using the replacement costs method should therefore be viewed with care. However, they do suggest that a monetary value imputed in this way for voluntary work could be situated at around the €12 to €17 billion mark, or 0.75% to just over 1% of GDP, depending on the variants of the method used.