The LAGEOS spacecraft is unique in that both its design and orbital characteristics were specifically chosen for high-resolution geodynamic studies using satellite laser ranging techniques. Since its launch in 1976, the precision of single shot ranging observations made on the satellite has improved from several decimeters to a few centimeters. With this level of precision it is possible to use LAGEOS data for studies of contemporary plate movement, polar motion, gravity, earth rotation, and earth and ocean tides. Inferences about mantle structure and dynamics, angular momentum coupling between the earth and its atmosphere, and perturbative effects acting on earth satellites are being extracted from the data. This special issue of the Journal of Geophysical Research presents the current research results derived from LAGEOS data.