Between 1819 and 1830, the Dutch moral reform society Maatschappij tot Nut van ’t Algemeen [Society for Public Welfare] failed to establish any long-lasting local branches in the Catholic southern part of the Netherlands. Thirty years later, an upsurge in the number of international social reform congresses rekindled the desire to establish southern sister organizations. In this article, Carmen Van Praet and Christophe Verbruggen argue that the congresses of the International Social Science Association (issa) from 1862 to 1865 played a vital role in bringing together intermediaries from across Europe. These international congresses offered a transnational space where attendees not only exchanged information about social reform experiments, but also contributed to the dissemination of association structures. During the Amsterdam congress of the issa in 1864, the principal Belgian advocates of secular education were strongly influenced by contacts with the advocates of Tot Nut. Shortly after this contact, the Belgian Ligue de l’Enseignement, an association aimed at improving education and establishing public libraries, was founded and was modelled on the associational structure of Tot Nut. The Ligue also maintained contacts with other single and multi-issue European organizations, resulting in an educational reform network of sibling associations. ‘Bondgenoten in de strijd’. Een relationele benadering van lokale en internationale onderwijsverenigingen in de jaren 1860 De Maatschappij tot Nut van ’t Algemeen slaagde er in de periode van het Verenigd Koninkrijk der Nederlanden (1815-1830) niet in om duurzame afdelingen te vestigen in het katholieke Zuiden. Dertig jaar later flakkerde de wens opnieuw op om inhet ondertussen onafhankelijke België zusterverenigingen op te richten. Vooral de internationale contacten tijdens de congressen van de International Social Science Association (issa) tussen 1862 en 1865 voedden dit verlangen. Deze bijeenkomsten brachten experts vanuit verschillende landen samen en waren ...