This proposal concerns a study on the concept of solidarity in general and international solidarity in particular and the shifting meanings given to it in Swedish and German Social Democracy between 1968-2019. Through a comparison of the role and changing meanings of the concept for Swedish and German social-democracy I aim to study struggle over the concept in two political parties, that had different positions during the time period. While Swedish social-democracy held government power for an exceptional amount of time, German social-democracy was mostly in opposition. A comparison of two parties, to a great degree ideologically and institutionally intertwined, could shed light on parallel conceptual shifts in relation to political influence. Hence this study is relevant to conceptual history as well as to labour history. Furthermore, I would also like to contribute to an underdeveloped field within conceptual history, as the focus primarily is placed on the linguistic level of the press, where conceptual history usually places only secondary interest. By anchoring conceptual analysis in a study of how the rise of solidarity movements influenced the conceptual practice of social democracy I hope to broaden the perspective of an oftentimes nation-centred labour history, to include an international and transnational view focusing on a part of the Baltic Sea region. My source material will primarily consist of newspapers and magazines. The press sources will be supplemented by party manifestoes and other programmatic and ideological texts. I will also study how the concept is used by social-democratic movements, such as womens- and youth organizations, Christian organizations and solidarity movements tied to the social democratic parties, so as to highlight the struggle for the concept. Preliminary conclusions include that since 2010, and especially since 2015, the concept of solidarity has regained some of its classbased connotations, in that certain more radical strands of social democracy have begun to use it to characterize their ideological core. Hence, the concept has been reconnected to some of its historical usages, for the purpose of formulating a politics for the future. Furthermore, it appears that the wider sense of the concept, in which it can refer to hospitality towards refugees, empathy with people suffering war or discrimination or climate crisis, is extremely volatile, its meaning shifting quickly, which makes it interesting to study how these shifts are reflected in social-democratic texts in which the concept appears. There has also probably occurred a change in the relation between solidarity’s subject and object since the seventies, as the concept has come closer to the Marxist definition, in which it is closely related to international fraternity, although not as heavily slanted toward class-based fraternity as in the Marxist definition.