This chapter outlines the general philosophical approaches underlying the research process, explaining what is meant by the concepts of ontology and epistemology, and the various standpoints that exist when considering the nature of knowledge and understanding. A number of approaches to understanding the nature of knowledge are presented, including positivism, post-positivism, critical realism and interpretivism. The chapter then describes the characteristics of (and relationships between) qualitative, quantitative, mixed methods, and deductive and inductive research, concluding with guidance in terms of choosing an appropriate approach.