Introduction Organizations have to cope with an increasingly turbulent environment requiring often rapid adaptation. Combined with the growing pressure from the economic system towards greater efficiency and often identical or at least highly similar technological processes, people become a crucial resource for organizational success. Without adequately qualified and motivated members an organization hardly can cope with these developments. In turn, this makes the management of human resources a crucial task for the management of an organization. In current HRM and management thinking, this is something of a no-brainer and belongs to common wisdom in HRM (see, e.g. Boxall/Purcell/Wright 2007). However, human resources are different from other resources in a number of ways: they have their own ambitions, they change constantly, they cannot be influenced in a straightforward and simple way, they react in surprising ways to external and internal stimuli, in other words: they are non-trivial machines (von Foerster/Brocker 2002 ). Linking the behavior of these non-trivial machines to the overall organizational goals is a difficult, yet essential task for successful management In the past, organizations mainly used standard employment to trivialize them, i.e. turn people into personnel with various kinds of capital that can be used for achieving organizational goals. HR-specialists played a major role in this when recruiting, training, appraising and compensating personnel, nearly exclusively interpreted as organizational members entering an explicit, labor-law based as well as an implicit psychological contract Linked with - and potentially caused by - a number of partly drastic changes in the organizational context, a new view of HRM reality ('what it is'), the impact of HRM (what it means) and the role and profile of HR professionals ('who it is') seems to emerge (see, e.g. Losey/Meisinger/Ulrich 2005). It goes far beyond this paper and the special issue to illustrate the broad spectrum of changes in the context as well as in HRM. However, we would like to emphasize three areas linked with each other that exemplify these changes: a greater variety in the employer-employee-relationships with organizations more often using capacities of people that formally do not belong to the company; this changing configuration of individuals constituting 'personnel' for organizations requires changes in the HR function; and, at a theoretical level, this also creates the need for further developing the concept of HRM. We argue that these changes - and, we hasten to add, many of the other changes that we can see in HRM - are a consequence of the shift from personnel management to HRM, i.e. they are built into the HRM concept. The concept of HRM As a concept, HRM emerged in the USA during the early 1980s. Two specific frameworks (Beer et al. 1985; Fombrun/Tichy/Devanna 1984) mark the start of the concept of HRM and, at the same time, the start for a partly heated discussion about the specifics of this concept and its relationship to personnel management (see, e.g., Armstrong 2000; Legge 2005; Sus 2004). Basically, however, there seems to be a fair degree of consensus about five major characteristics of the HRM concept. First, HRM emphasizes the necessity of integrating HR activities across a variety of functions and with the organizational strategic orientation (Boxall/Purcell 2003; Schuler/Jackson 2000; Lengnick-Hall/Lengnick-Hall, 1988). In practice, we see a 'two camp landscape' in HRM. In one group of organizations, HRM clearly is an integral part of the strategic processes, playing a role already in the early stages of the process and being a valued player. In another group, HRM has an important role, but is clearly subordinate. It plays a role in strategic processes only at a later stage. Second, line managers play a crucial role in the concept of HRM. Linked to general developments such as new organizational forms (Whittington et al. …