The phenomenon of glacial isostatic adjustment (GIA), with its unique temporal and spatial signatures, provides one of the great opportunities in the geosciences for obtaining information about dynamic Earth processes. GIA contains information about recent climate forcing, being dependent on the geologically recent loading and unloading of ice sheets. It presents a unique opportunity to study the dynamics and rheology of the lithosphere and mantle; is responsible for substantial sea level variations; and is of fundamental importance to geodesy because site positions, reference frames, Earth rotation, and gravity are all influenced by GIA.The Global Geodetic Observing System (GGOS) of the International Association of Geodesy and the International Lithosphere Program's Regional Co‐ordination Committee Upper Mantle Dynamics and Quaternary Climate in Cratonic Areas (DynaQlim) jointly organized a workshop that attracted 36 international scientists to Finland. The objectives of this workshop were to (1) review the current state of the science in modeling GIA, (2) review the use of geodetic measurements to constrain and test GIA models, (3) identify obstacles to improving GIA models, and (4) identify improvements to the global geodetic observing system that are required to better understand GIA.