During the last ~100 years, tectonic geodesy has evolved from sparse field-based measurements of crustal deformation to the use of space geodetic techniques involving observations of satellites and from satellites orbiting Earth, which reveal a variety of tectonic processes acting over a wide range of spatial and temporal scales. Early terrestrial measurements using triangulation and leveling techniques characterized large displacements associated with great earthquakes and led to the recognition of the fundamental mechanics of seismic faulting and the earthquake cycle. More precise measurements using ground-based laser ranging allowed for the characterization and modeling of interseismic strain buildup and determination of slip rates on major faults. Continuous and highly accurate point measurements of strain, tilt, and fault creep have captured intriguing deformation transients associated with slow slip events on active faults. The greatly improved precision, spatial and temporal resolution, global coverage, and relatively low cost of space geodetic measurements led to a revolution in crustal deformation measurements of a range of tectonic processes. Very Long Baseline Interferometry, the Global Positioning System, Interferometric Synthetic Aperture Radar, and space-based image geodesy complement each other to comprehensively capture tectonics in action at scales ranging from meters to global and seconds to decades. Space geodetic measurements allow for the precise measurement of global plate motions, the determination of strain rate fields and fault slip rates in distributed plate-boundary deformation zones, and characterization of subtle intra-plate deformation. These measurements provide increasingly important constraints for earthquake hazard studies. Space geodesy also allows for the recognition and detailed model exploration of a number of transient deformation processes during the post-earthquake deformation phase of the earthquake cycle. Measurements of postseismic deformation transients provide important insights into the mechanisms, rheological properties, and dynamics of crustal deformation. Increasingly, seafloor geodetic measurements provide information about deformation on the 70% of the Earth's surface that were previously inaccessible. Future improvements of modern geodetic techniques promise to further illuminate details of crustal deformation at all spatial and temporal scales, leading to an improved understanding of the dynamics of active tectonics.