This volume brings together for the first time case studies on secularists of the 19th and early 20th centuries in national and transnational perspectives including examples from all over Europe. Its focus is on freethinkers taken as secular avant-gardes and early promoters of secularity. The authors of this book deal with multiple historical, religious, social, and cultural backgrounds and, in these contexts, analyze freethinkers' organizations, projects, networks, and contributions to forming a secular worldview, in particular, the promotion of concrete undertakings such as civil baptism or initiatives to leave church. Next to this secularist agenda, the contributions also take into account ambivalences and difficulties freethinkers were faced with, namely, the tensions between a national self-image and the transnational direction the movement has taken; the regional base of many projects and their transregional horizon; freethinkers' cultural programs and their immanent political mission; and the dialogue with respectively the conceptual distinction from other secularist groups. Readers interested in the history of secularity will learn that it was a heterogeneous enterprise already in its beginnings. This set the course for later European and global developments.