  In this paper, we present the work of international mathematical
associationism carried out by the mathematician from Navarra (Spain) Zoel
Garc\'ia de Galdeano (1846-1924) during over 30 years. Garcia de Galdeano was a
member of many of the most important mathematical associations of his time,
thus being able to be in touch with foreign mathematicians of high level and to
exchange ideas, works and collaborations. This work of associationism has been
unnoticed in biographical and scientific studies up to now and helps to
complete the picture of Garc\'ia de Galdeano as an international mathematician
and as a wise importer of the main mathematical achievements of his time.
