In 1922 Santillán represented FORA at the formation of the anarcho-syndicalist International Workingmen's Association (IWMA) in Berlin; while there he began to study Medicine, and came to know Elise Kater, who was to become his wife. The first of many works on the history and theory of anarchism were published at this time – "Ricardo Flores Magón: Apostle of the Mexican Social Revolution" and "Anarchism in the Labour Movement" both appeared in 1925.