What determines the resources allocated to an HR department? The antecedents of the size of HR departments within firms and the relationship between HR department size and the role that HR departments perform are issues of theoretical and practical importance. Using large-scale survey data from organizations in Europe and Japan, this article explores the influence of nationality, size, and sector on the comparative ratio of HR specialists in organizations, and on the likely scope and brief of such departments. It also examines the internal organizational characteristics associated with HR department size. In contrast to previous literature on administrative components, we demonstrate that the human resources staff component is affected not only by organizational size but also by sector and national location. © 2006 Wiley Periodicals, Inc.