Volunteers are playing a growing and increasingly important role in organisations across all three sectors: public and private as well as third. Their contribution to third sector organisations is (on one level at least) fairly straightforward – the theoretical framework developed by David Billis (2010) identifies volunteers as the sector’s distinctive human resources – but the position with regard to the organisations in the other two sectors is more problematic. For Billis the private sector’s distinctive human resources are ‘paid employees’ while the public sector is staffed by ‘paid public servants’ (ibid., p. 55). Within Billis’s framework the presence of volunteers in these two sectors is in a sense anomalous and may indicate that an organisation in which they are involved contains elements of hybridity. In this chapter we discuss the role and status of volunteers in different kinds of organisation and review the ways in which their activities are organised. We have carried out this review in order to assess the extent to which the involvement of volunteers can be seen as a way of defining organisations as hybrid. Our discussion is largely centred on the experience of volunteering in England, although we will also take account of some relevant literature from elsewhere. Direct evidence of the changing nature or experience of volunteering in hybrid organisations is hard to find. Some commentators have discussed the implications of hybridity for volunteers within the third sector (see Hustinx, 2014; Ellis Paine et al., 2010) but there is less discussion of volunteering within other hybrid settings. Indeed, even within the field of third sector studies, as Warburton and McDonald (2009, p. 825) argue, ‘little is known about how these organisational changes impact upon the capacity and commitment of volunteers, and particularly those volunteers accustomed to working in a traditional institutional order’.