Industrial relations are widely regulated by law in France, while the British system is essentially voluntaristic. More broadly, the structures, strategies and ideologies of social actors in the two countries differ profoundly. Comparative statistical analysis, based on two similar workplace industrial relations surveys (WIRS 90 and REPONSE 92), sheds some light on the internal logic of each system. Our results show that while British unions, in the establishments where they still exist, certainly have more members and more formal involvement in management decisions, their French counterparts are present in a larger proportion of establishments, and have a greater ability to mobilize workers for conflict when they find it necessary.