Geochemical interactions of actinide colloids are of vital importance to understanding the migration of actinides in natural aquifer systems. Much effort has gone into quantifying the migration of colloids and, subsequently, to applying these quantities to hydrodynamic and geochemical modeling. An overview of recent progress in the investigation of migration behavior of actinide colloids in natural aquifer systems is presented. The impact of pseudocolloid generation on actinide migration is also discussed and illustrated with the results obtained in recent studies.