The political groups of the European Parliament (EP) play a diplomatic role in terms of the EP’s legislative powers, their rhetorical role in European Union (EU) foreign policy, and through direct diplomatic action in third countries. It is therefore surprising to observe that the parliamentary diplomacy of the political groups – conceived as diplomatic activities that are conducted by parliamentarians – is an under-researched area of study on parliamentary diplomacy and the EU’s Common Foreign and Security Policy (CFSP). This paper therefore seeks to better understand the diplomatic role of the EP’s political groups. To this end, this paper seeks to answer two over-arching questions: first, what diplomatic role/s do the political groups play in the parliamentary diplomacy of the Parliament? Second, what overall impact do these diplomatic role/s have on the EU’s CFSP? Based on these questions, this paper provides an analysis of the weaknesses and strengths of the political groups when engaged in diplomacy, and it outlines the benefits and drawbacks of having the political groups engage in international affairs.