Firn compaction, where snow transforms into glacial ice, is an important and fundamental glaciological process. Accurate models, and observations to calibrate those models, are essential for many applications including conversion of satellite altimetry data into ice mass estimates, estimating the meltwater storage capacity of firn aquifers, and interpreting ice-core paleoclimate records. This session brings together observational, experimental, and modeling studies of firn and focuses on the advancement of our understanding of the firn compaction process. We invite contributions from all aspects of firn research and particularly welcome studies of i) advances in firn observational methods, ii) remote sensing of firn, iii) firn model assessments, iv) laboratory measurements of firn properties, and v) development of physics-based firn models.