Constraining the present-day interior structure and dynamics of giant planets is critical to understanding the formation and evolution of planets in our Solar System and beyond. Both the ongoing Juno mission and the recent Cassini mission have provided a wealth of new measurements, revealing key aspects of the interiors of Jupiter and Saturn for the first time. Further, new discoveries about Uranus, Neptune, and exoplanets continue to expand our horizons. This session will bring together observations and theory to improve our understanding of giant planet interiors. We welcome submissions on a range of interior topics, including: gravity; differential rotation (zonal flows); dynamo magnetic fields; the existence and properties of the central core; seismic, thermal, and magnetic consequences of stable stratification; normal modes; bulk composition (including helium and heavy elements); and formation scenarios or evolutionary pathways. Abstracts may focus on a single gas/ice giant, or comparisons between multiple bodies.