A large theoretical literature has characterised co-operatives through two main deficiencies: a low flexibility and low average skills (rationalisation). These authors conclude that it induces a low capacity to optimise the use of their resources, that is to say a low efficiency (results may be weaker than what their resources could produce). However, the empirical literature has not confirmed a significantly lower level of efficiency for co-operatives. Moreover, the latter are far from disappearing, which means that they are competitive. A survey of the empirical literature and new data on French co-operatives show that the diagnostic on deficiencies was right but that their inferences were wrong, since they overlooked alternative sources of efficiencies. On one hand, difficulties of coordination with the markets occur due to co-operatives' lack of flexibility and rationalisation. On the other hand, these deficiencies foster the emergence of another source of efficiency, based on a deep knowledge of the activities by and between the actors, and protect the co-operatives from the current excessive instability of the economic system. Local efficiencies create co-ordination problems with external actors, but these offset each other rather than create ongoing inefficiencies.
