Ultra-low frequency (ULF: 1mHz to 5 Hz) waves are ubiquitous in the solar-terrestrial environment and have been recognized to play an important role in modulating energy and density of magnetospheric plasma and energy transfer from the solar wind to planetary magnetospheres and ionospheres. ULF waves can be driven by external sources such as interplanetary shocks and upstream waves/transients. They can also arise from various sources that are internal to the magnetosphere such as localized instabilities. Recent studies have shown that ULF waves can modulate ionospheric parameters, drive geomagnetically induced currents, and affect the radiation belt and ring current particle populations. Multipoint spacecraft measurements, increasing coverage of ground-based instruments, recent development of geospace models, have enabled significant advances in ULF wave research. This session invites presentations examining the causes and consequences of ULF waves in planetary magnetospheres (e.g., Mercury, Earth, and Jupiter) through observations, modeling, and theory development.