This chapter examines how actors and structures make foreign policy an extremely complicated field of study and how, in view of this complexity, these actors and structures have been treated in the literature on foreign policy analysis. It first provides a historical background on the field of foreign policy before discussing the role of actors and structures in ‘process’ and ‘policy’ approaches to foreign policy. In particular, it describes approaches to foreign policy based on a structural perspective, namely: realism, neoliberal institutionalism, and social constructivism. It then considers evaluates approaches from an actor-based perspective: cognitive and psychological approaches, bureaucratic politics approach, new liberalism, and interpretative actor perspective. The chapter also looks at the agency–structure problem and asks whether an integrated framework is feasible before concluding with a recommendation of how to resolve the former in terms of a constructive answer to the latter.