In this chapter, the argument will be made from a realist perspective that it is at the level of practice/intervention that the interconnectedness and interdependency of systems are revealed with particular clarity, confronting practitioners with the reality of what complexity is and means, and its potentially overwhelming impact. In this chapter, the argument is made that the task for human service workers at the service delivery level is to deconstruct complexity, both to make action possible and to enable creative and innovative responses to problems. In particular, the focus of an interdisciplinary team might be on disentangling knowledge, values and interests in order to find common ground for action. A model of reflection-on/in-practice is described, which utilises the interaction of the team itself as a source of insight and the location where the team members’ hypotheses for determining actions are shared and examined. The argument for a ‘new’ type of human service provider, one who is a specialist or expert in working across systems, will be considered with reference to the kind of training that might be required. David Byrne's (1998, 2009) arguments for a realist (post-positivist) perspective on researching complexity will be examined, allied with the work of Pawson and Tilley (1997, 2004).

The real world of the practitioner

Let us begin this discussion of the relationships among complexity theory, interdisciplinary working and reflective practice by considering a fairly typical scenario confronting a social worker in a multidisciplinary health team working in a hospital rehabilitation ward: