This study explores why the subsidiary line managers of multinational companies (MNCs) implement HRM practices differently than intended by headquarters. HRM implementation is understood as a process in which one has to differentiate between a range of multifaceted HRM implementation scenarios. We build on a single case study in a Dutch subsidiary of a US engineering company that we characterised as an extreme case. The analysis comprises in-depth interviews with HRM and line managers and a study of policy documents using multiple iteration cycles with the software ATLAS.ti. Line managers engage in a range of behaviours: they ignore, deviate, imitate, internalise, initiate and/or integrate the delegated practices because they fail to see the value of the content of the practice and the process of execution. The HRM implementation scenarios found, although distinctive, often overlap, evolve or coexist in a dynamic HRM implementation process. We predict a support role for HRM managers in which they facilitate line managers in deviating from intended practices, and initiating new ones, in order to increase the likelihood of successful internalisation and integration.