The ISO international congresses which take place every other year are major events on the calendar during which members spend a week studying a particular organbuilding tradition in a friendly and congenial atmosphere. Each time we meet in a different country to discover local instruments, to learn about their history and way of organbuilding, and to visit member's workshops.

Recent congresses have included such prestigious locations as Switzerland (2012), Transylvana Romania (2014), London (2016), Austria (2018), Strasbourg (2023) bringing together up to 200 organbuilders and their families on each occasion. 

The 32st World Congress of Organ Builders will take place 2025 in Stockholm.