This chapter offers responses to the question ‘why regulate?’ and ‘why do regulatory regimes emerge in a particular form?’ by examining ‘theories of regulation’. While chapter 1 introduced the readers to the economic justifications of regulation, this chapter delves into the different theories that explain why we need regulation and how public and private actors interact to shape the content of regulation. These theories refer to a set of propositions or hypotheses about why regulation emerges, which actors contribute to that emergence, and typical patterns of interaction between regulatory actors. It discusses theories from several disciplinary approaches, classifying these theories into four kinds: public interest, private interest theories, systems and institutionalist approaches and ‘hybrid’ theories.

Social workers will often say that they use systems theories in their practice. People are inextricably linked to their environments, and theories that call on systems of experience and interaction tend to make logical and practical sense to workers in daily practice. Systems theories help us to think about these interactions between people and their social and physical environments, and they also help us to understand how change can occur through the use of ecosystem interventions.In this chapter, we will explore the development of systems theory and how some key thinkers in the systems theory approach have informed social work practice. An examination of some of the key systemic thinkers and their understandings of systems theories will serve to illustrate how these theories have evolved, and how they have shaped practice in different and significant ways. Finally we will explore contemporary systemic adaptations, and in particular, how a broader systems analysis informs service navigation.