This paper describes a dichotomy between the contexts in which different job roles are performed: boundaried and non-boundaried contexts. We have drawn the distinction to explain particular patterns of activities, responsibilities, work environments, team organisation, management and other factors in different frontline roles within high reliability organisations – patterns that seem to cross industry domains. We believe that this distinction is useful as non-boundaried job roles tend to be under-represented in the design and management of systems, despite their important contribution to the integrity of the organisation.