Prior research has produced ambiguous support for theories on the nature and construction of Human Resource Management (HRM) systems. This ambiguity may be a function of the inherent limitations of the methodologies used in previous studies. We resume efforts by using a configurational methodology to analyze high performing HRM systems of 374 UK based firms. We reveal the multi-dimensional nature of successful and unsuccessful HRM systems. By providing a typology for comparing the interdependencies among vital and peripheral functions, we are able to describe and explain competitive advantages that rest in the orchestrating themes and integrative mechanisms of HRM systems.