Within the public sector great change efforts are currently made to meet future challenges. In the area of health care, change initiatives are implemented to enhance quality and efficiency. To this end, a lean change programme is being widely introduced in Sweden as well as internationally. The overriding aim of this study is to increase knowledge of what happens when change programmes, CP, such as lean are implemented in a healthcare organisation, HCO. Previous research has shown that the main obstacle to implementing CP in HCO:s is their complexity. However, the complexity has often been reduced, as different factors such as management, professions, organisation and control have been studied separately. To fully capture the complexity of the HCO the Actor Network Theory, ANT, was used in this study. In line with ANT, introducing lean can be described in terms of a translation process in which human and non-human actors are woven into a network. This approach allows for the incorporation of various factors in the study of a change process in a complex organisation. Drawing on ANT, this thesis explores how network constructions enable or impede change programmes. The approach is based on ethnographic monitoring of the implementation of lean in the Värmland county council public healthcare organisation. As a result of the holistic perspective, the study provides detailed descriptions of how complexity impacts on the implementation. It displays the relations enabling or impeding the implementation of CP and the methods actors use to establish and defend the relations. The contribution of the study is threefold. Empirically, the study monitors a HCO aiming to implement full-scale lean as philosophy, principle and tool. Methodologically, the study evaluates ANT as a methodological theory to study CP in a HCO. Finally, the domain-specific contribution of the study is its identification of the relations and methods that impact on lean deployment. / Kan förändringsprogram från den japanska bilindustrin lösa framtidens utmaningar inom hälso- och sjukvården? Ja, tycks svaret på frågan vara. Allt fler hälso- och sjukvårdsorganisationer väljer nämligen att införa och tillämpa lean i hopp om att öka kvalitet och effektivitet. I denna bok följer Stefan Hellman införandet av lean i ett av Sveriges landsting.   Tidigare forskning visar att förändringsprogram som lean kan resultera i positiva effekter när det införs i hälso- och sjukvården. Införandet är emellertid förknippat med problem. Hellman visar att det både finns anhängare och motståndare till lean. Han intervjuar och observerar anhängarna och motståndarna och identifierar därigenom hur de går tillväga för att underlätta respektive försvåra införandet av lean. Därigenom ger Hellman en inblick i hälso- och sjukvårdens komplexitet och visar vilka konsekvenser den ger när förändringsprogram införs i praktiken.