Purpose: This paper aims to analyse, through the lens of learning network theory, ways in which external VET practitioners work within private enterprises to promote learning within these organizations. Design/methodology/approach: The paper is based on analyses of six case studies in two Australian States, each comprising a vocational education institute and an enterprise. In total, 34 interviews were held with four groups of participant--TAFE managers and practitioners, enterprise personnel and worker-learners--from different industries. Findings: The paper finds that the overlaying of an external learning system on existing learning systems brings inevitable tensions that need to be carefully managed. VET practitioners working in industry operate in two worlds with very different cultures. They need to learn how to work within different power structures, how to build around existing work and learning networks, and how to mesh in with the flow of enterprise work. In the process of working with company staff, and crossing boundaries, they may well be creating a "third space" in which new meanings can be, and have to be, constructed that go beyond the limits of either site. Practical implications: The paper shows that understanding these ways of working has practical implications for VET managers and practitioners, company staff and policy-makers in terms of how human resources are managed and how different parties work together. Originality/value: The paper shows two objectives: a relatively new focus in the research literature and an extension of learning network theory in terms of external learning systems.