The electoral behavior of Swedes in the parliamentary elections of September 9th, 2018 will provide new insights into the state of public opinion in a Europe facing the challenges of immigration and integration. This paper discusses the “Sweden Democrats”, a nationalist and anti-immigration party whose breakthrough in 2010 has been confirmed; the author analyzes the evolution of this party, its sociology, the reasons for its success, its position within the Swedish political system and the consequences of its increasing influence on the future of Sweden. The English version of this study is available on the Foundation for Political Innovation’s website (fondapol.org).