Objective Safe hospital discharge relies upon communication and coordination across multiple occupational and organizational boundaries. Our aim was to understand how these boundaries can exacerbate health system complexity and represent latent sociocultural threats to safe discharge. Methods An ethnographic study was conducted in two local health and social care systems (health economies) in England, focusing on two clinical areas: stroke and hip fracture patients. Data collection involved 345 hours of observations and 220 semi-structured interviews with health and social care professionals, patients and their lay carers. Results Hospital discharge involves a dynamic network of interactions between heterogeneous health and social care actors, each characterized by divergent ways of organizing discharge activities; cultures of collaboration and interaction and understanding of what discharge involves and how it contributes to patient recovery. These interrelated dimensions elaborate the occupational and organisational boundaries that can influence communication and coordination in hospital discharge. Conclusions Hospital discharge relies upon the coordination of multiple actors working across occupational and organizational boundaries. Attention to the sociocultural boundaries that influence communication and coordination can help inform interventions that might support enhanced discharge safety.