The authors of The Machine that Changed the World were in no doubt about the importance of teamworking in lean production: ‘in the end’, they say [Womack, J., Jones, D, & Roos, D. (1990). The machine that changed the world. New York: Rawson Associates, p. 99], ‘it is the dynamic work team that emerges as the heart of the lean factory’. It is with this bold statement in mind that we seek to explore and develop our conceptual and practical understanding of how teamworking operates under Lean. We examine these issues in the context of a high-profile case of Lean implementation in the UK public sector, the Pacesetter programme of the UK's tax assessment and collection service, Her Majesty's Revenue & Customs (HMRC). We find that although the teams themselves were ostensibly set up on a lean basis, they were largely unable to operate as such as a result of the pressures they faced to meet their work targets. The operation of the teams thus retained, and was shaped by, characteristics of the pre-existing ‘target-based’ mode of teamworking. This, in turn, suggests particular ways in which we might better understand how Lean interacts with the context or environment into which it is introduced. These findings also to some degree run counter to the overwhelmingly negative account of Lean put forward in other recent studies of HMRC [e.g. Carter, B., Danford, A., Howcroft, D., Richardson, H., Smith, A., & Taylor, P. (2013a). Taxing times: Lean working and the creation of (in)efficiencies in HM Revenue and Customs. Public Administration, 91, 83–97].