Workshops are selected by the ISSI Directors in consultation with the Science Committee. The programs and speakers are defined by a group of highly qualified experts serving as convenors. The Workshops of a week duration (in exceptional cases repeated) can be attended by 40-45 invited scientists and experts. The results of the Workshops are published as refereed papers in issues of Space Science Reviews and in parallel as volumes of the Space Science Series of ISSI (SSSI).