This SE helps doctoral candidates to find an appropriate theory of international relations for their theses. It also will make suggestions how to apply it to specific cases studies. In the first step the major IR Theories will be introduced by the lector and the students themselves. They include among others (neo)realism, liberal institutionalism, regime theory, English school, constructivism, interdependence and integrations theories, democratic peace, security communities. In the second step the theories will be tested on some cases. In the third step the students make one or more choices for their individual topics. They discuss the best way how to apply the theories to their cases.