The Swedish Institute is a public agency promoting Swedish interest, national image and confidence around the world. This work attempts to investigate how communication and a process over time influences and effects public diplomacy. The analytic discussion is based on a single case study research of this Institute representing ideas in the international science field of public diplomacy. The theoretical ideas of public diplomacy are placed in a theoretical perspective of social constructivism. The method is qualitative, with excerpts taken from interviews, literature, newspapers, articles, state public reports and social media. The work adopts a discourse analytic approach, aiming to uncover the structure of public diplomacy by using three analytic tools: soft power, nation branding and cultural diplomacy. The presented analysis and examples suggest a close collaboration between researchers and practitioners can lead to a coherent theory of public diplomacy. The result identifies promising directions as well as weakness and gaps in existing knowledge. The work promotes an analytic tool “korstryck” for theorize and conceptualize the discussion of public diplomacy. A strategy of today requires three fundamental components: power, diplomacy and communication. The challenge in public diplomacy is the balance between public opinion, public foreign policy and global networks of communication. The paper aims to open doors for further scientific works are needed in the searching for a theory of public diplomacy.