This chapter addresses a central question for Australian political science: can political scientists use the same theories to explain Australian domestic politics and Australia’s international activities, or do they need different theories to understand each sphere? As the chapter shows, the answer depends to some extent on which theories political scientists adopt to explain domestic and international politics. Realists, for example, point to the absence of a world government to claim that the fundamental problem of international politics – anarchy – is different from the problems raised by domestic political systems with legitimate governments. On the other hand, as a comparison of this chapter with Chapters 4 and 5 will show, Marxists, feminists and discourse theorists use many of the same concepts and approaches to understand domestic politics and international politics. The connections between liberal international relations theory and institutionalism (Chapter 3) will also become obvious to careful readers. Finally, this chapter reiterates the point, made in Chapter 1, that many domestic policy issues are affected but not determined by international power relations.