The IAU runs its 10-day duration General Assembly (GA) every three years.

This event is a unique opportunity for astronomers working in all fields of astronomy to come together. Besides the General Assembly per se with its administrative meetings, the scientific programme usually comprises 2 series of 3 Symposia of 3.5 days duration each, scheduled during the first and second weeks, respectively. During the 10-day period, a number of Joint Discussions are held, typically about 15-20 total, with up to 5 running in parallel. Special Sessions on specialized and timely topics are also organized.