Background: Relatively little is understood about real-world provision of oncology care in ambulatory outpatient clinics (OPCs). This study aimed to: 1) develop an understanding of behaviours and practices inherent in the delivery of cancer services in OPC common areas by characterising the organisation and implementation of this care; and 2) identify barriers to, and facilitators of, the delivery of this care in OPC common areas. Methods: A purpose-designed ethnographic study was employed in four public hospital OPCs. Informal field scoping activities were followed by in-situ observations, key informant interviews and document review. A view of OPCs as complex adaptive systems was used as a scaffold for the data collection and interpretation, with the intent of understanding ���work as done���. Data were analysed using an adapted ���Qualitative Rapid Appraisal, Rigorous Analysis��� approach. Results: Field observations were conducted over 135 h, interviews over 6.5 h and documents were reviewed. Analysis found six themes. Staff working in OPCs see themselves as part of small local teams and as part of a broader multidisciplinary care team. Professional role boundaries could be unclear in practice, as duties expanded to meet demand or to stop patients ���falling through the cracks.��� Formal care processes in OPCs were supported by relationships, social capital and informal, but invaluable, institutional expertise. Features of the clinic layout, such as the proximity of departments, affected professional interactions. Staff were aware of inter- and intra-service communication difficulties and employed strategies to minimise negative impacts on patients. We found that complexity, coordination, culture and capacity underpin the themes that characterise this care provision. Conclusions: The study advances understanding of how multidisciplinary care is delivered in ambulatory settings and the factors which promote or inhibit effective care practice. Time pressures, communication challenges and competing priorities can pose barriers to care delivery. OPC care is facilitated by: self-organisation of participants; professional acumen; institutional knowledge; social ties and relationships between and within professional groups; and commitment to patient-centred care. An understanding of the realities of ���work-as-done��� may help OPCs to sustain high-quality care in the face of escalating service demand.