Background: The burden of breast cancer is a key challenge for women's health globally. Rehabilitation needs and strategies for living with long-term consequences of breast cancer and its treatment cannot be isolated from the social contexts of patients, including relationships with relatives and healthcare professionals. Aim: This study explores how healthcare professionals’ categorisations engage with breast cancer patients’ social identities in encounters about rehabilitation before hospital discharge. Method: We conducted a multiperspective case-based qualitative study at a Danish department of breast surgery, including participant observations and interviews with twelve patients and eight nurses. Data were analysed thematically using theories of categorisation and clinical encounters. Ethical considerations: The Danish Data Protection Agency approved the study (journal number 2012-41-0701). Results: Interactions in clinical encounters are shaped by categorisations of patients’ social identities in terms of social resources and ethnicity, and by the resource-constrained organisational context, with impact on the assessments of the patient's rehabilitation needs. Conclusions: There is a need for a greater focus on improving encounters between breast cancer patients and healthcare professionals to ensure that rehabilitation needs are accommodated for among diverse patient groups.