People with complex chronic conditions frequently need to navigate their own way through and around a fragmented and siloed health care system. Care coordination is a defining principle of primary care and is frequently proposed as a solution to this problem. However, care coordination requires more time and effort than primary care physicians alone have the capacity to deliver. Although registered nurses are skilled team members who can be included in the delivery of coordinated patient care, any model of care coordination that involves registered nurses needs to fit within the existing health care delivery system. In this study, which used qualitative techniques based on grounded theory and included face-to-face interviews and open coding and theoretical sampling until data saturation was achieved, and which was one component of a larger action research study, we aimed to gain an understanding of the difference between usual chronic condition care and the work of chronic condition care coordination. The researchers interviewed general practitioners and registered nurses from various general practice sites who were actively coordinating care. Four unique processes were found to define care coordination implementation, namely,(1) moving beyond usual practice by spanning boundaries,(2) relationship-based care,(3) agreed roles and routines among relevant parties and (4) committing to chronic condition care coordination. The findings suggested that existing professional and organizational cultures required negotiation before care coordination could be integrated into existing contexts. The challenge, however, seems to be in acknowledging and overcoming professional practice boundaries that define existing care through reflective practice and shared resourcing.