This exploratory case study research applies a processual analysis (Pettigrew, 1997) to the implementation of a Customer Relationship Management (CRM) system from a knowledge management perspective to a contemporary (1999-2004) situation within Birmingham City Council. A specific focus is given to areas neglected in previous CRM studies - sub-cultures, psychological contracts, how tacit knowledge is surfaced and transferred, and with what effects on implementation. It investigates how the system stakeholders and the information system (IS) itself evolved through encountering barriers, sharing knowledge, finding new uses, inventing work-arounds. A rich picture emerges of sub-cultural silos of knowledge linked with psychological contracts and power-based relationships influencing and inhibiting adoption and acceptance of the CRM system.