This paper propose a chart to assess the qualitative effetcts of cooperation among libraries. First, we have introduced the theoretical plat-form which guided us, on one hand, in accomplishing a field-study in the network of libraries associated with the french national library ; on the other hand, in setting up the assessement indicators of cooperation qualitative effects. This plat-form is made up of a network model as a three-dimensions relating machine (infrastructure, infostructure and infoculture) and of three levels of localising the qualitative network effects on a library, which are the library relationship with its external environment, its services offer and its internal environment. Second, we have relied on the field-study results to introduce a series of questions that the evaluator has to ask in order to obtain the indicators of qualitative effects. Finally, these indicators have been compared to referents (norms, standards, pre-defined