The effectiveness of CRM systems is still highly debated in management and marketing studies. The goal of this paper is to shed light on what the main factors and dimensions that affect the effectiveness of CRM systems are. Moreover the Authors are interested to investigate on what is the relationship between CRM adoption and expected performances. Methodologically, we refer to the use of a single case study for showing how CRM has been implemented, adopted and critically re-organized by a medium-sized b2b company. Our findings clearly show that CRM systems are strongly influenced by social as well as organizational dimensions which might or not might link to the complexity of the technology implemented. Moreover, the case shows that positive performances of CRM vary considerably depending on the attitudes and behaviours of the investigated users considered. The paper identifies future research avenues in the field of CRM in business-to-business markets.