Inclusion and exclusion are often understood in dichotomous terms, i.e., as a pair of words referring to essentially different actions or results. Some are included whereas others are not – either you are in or you are out. I claim, however, that perceptions of inclusion and exclusion as rigid opposites are at risk of contributing to ahistorical and anachronic representations of ideas and knowledge. In my presentation, I draw upon my doctoral dissertation, in which I study Finnish social and health organisations as experts, knowledge producers and policy actors in the 1930s–1960s. Through selected examples, I illustrate how non-governmental actors have constructed ideals and problems as well as policies for furthering a desired development. In a Koselleckian streak, I analyse the actors’ horizon of expectation; their visions for future Finland. These ideas and visions have been intertwined with various ideologies and ideas, such as nationalism and racial hygiene, and shaped by past events and experiences. I argue that inclusion and exclusion have been central notions in the making of the Finnish welfare state. Moreover, I argue that the importance of these notions is best understood by analysing them as historical and political concepts, rather than treating them as descriptive and analytical labels. By this, I mean approaching inclusion and exclusion as intertwined, fluid and fuzzy ideas whose meanings and usage vary according to time and actor. In conceptualising and developing public policy ideas, knowledge and practices, various actors have targeted individuals and groups of people according to a myriad of inclusive and exclusive labels and categories. While these labels and categories have constructed boundaries between people, inclusion and exclusion should also be seen as nuanced, flexible and contested ideas that are in interplay with each other. A seemingly exclusive practice, such as compulsory sterilisation on social or eugenic grounds, may also be understood as a channel for inclusion, or as being based on long-term ideas of inclusion (or prevention of exclusion). Respectively, a closer examination of seemingly inclusive key concepts in welfare state development, such as ‘people’ or ‘universal’, may reveal various notions of exclusion. In other words, inclusion and exclusion have not always been mutually exclusive categories, but co-existing and intertwined ideas.