Locked inside both terrestrial and extraterrestrial materials are records of ancient magnetic fields that, if faithfully unlocked, can yield immense insights into planetary processes, the evolution of the early solar system, the driving mechanisms controlling the future of our protective geomagnetic field. This session welcomes a broad spectrum of contributions in the advancement of absolute or relative paleointensity theory, measurements, and results. We welcome contributions that develop new models, simulations, instruments, experimental techniques, and analytical approaches to better estimate absolute and relative paleointensities. We also welcome complementary approaches that help us to obtain accurate paleointensities, including but not limited to rock magnetic, microscopic, and petrological studies.