This article focuses on the influence of activist ideas on perceptions of professional identity and professional practicewithin the field of library during the 1970s and the 2010s. The main empirical material consists of articles publishedin the journal Bibliotek i Samhälle (bis). It is distributed by the socialist organization Bibliotek i Samhälle (BiS) thatwas established 1969 and is considered to be the most distinguished exponent of a political based professional iden-tity within the library field in Sweden. In our analysis, we problematize the influence of activist ideas in perspectiveof ideals of democracy, freedom of speech and legitimacy of the public sector. Another central objective is to identifyexpressions of “zeitgeist” (the era-defining and dominant public spirit) that have inspired BiS, for example, Marxist,egalitarian, norm critical or anti-racist ideas.The article explores how certain narratives have been included or excluded in perceptions of professional identityand practice, and discusses expressions of continuity and change. In the 1970s Marxist ideas and the notion of anongoing class struggle was main guiding principles for BiS-activists. To a significant extent, these classical socialistconcepts have been replaced by antiracism, non-discrimination and identity politics. We present four different mod-els of librarians as civil servants: The bureaucratic, the ethical professional, the activist and the entrepreneurial idealtype. With empirical examples, we demonstrate that the activist librarian has historically argued and acted as an ide-ological gatekeeper, for example in questions concerning selection of literature. This article can benefit our under-standing of a political based concept of the public library; a concept, which has its ideological roots in the spirit of1968 and still, 50 years later, is of importance.