Focusing on three factors: organization and leadership, ideology, and external responses this essay explores why some right-wing extremist parties become politically established. Through a comparison of the Sweden Democrats (SD) and the Nordic Resistance Movement (NMR), the study examines how the three factors influence political success. SD evolved into Sweden’s second largest party, gaining a considerable political influence, while NMR remains outside the political mainstream and is labeled a terrorist group by the US government. To fulfill the purpose of this essay, four research questions are posed based on the three focus areas. The questions are: (1) What does the development of organization and leadership look like for the Sweden Democrats and the Nordic Resistance Movement? (2) What does the ideological development look like for the Sweden Democrats and the Nordic Resistance Movement? (3) How has the external response to the Sweden Democrats and the Nordic Resistance Movement evolved? (4) To what extent have organization and leadership, ideology, and external responses influenced whether these movements have become established political parties or not? Findings of the essay reveal that all of the focus areas play critical roles in determining whether a movement becomes established or not. The essay concludes by recommending further research on additional movements, European contexts, or left-wing extremism is needed to reach a more unified picture of the research area.