Seismic surface wave data have been used to infer details of earth structure over various propagation paths. Experimental methods for measuring surface wave dispersion include the Fourier phase method, the time correlation method, the band‐pass filtering method, the group delay time method, and various digital ‘moving window’ techniques. Surface wave data exhibit distinctive observational characteristics for different tectonic provinces such as shields, aseismic continental platforms, rifts, oceans, and mountains. Inversion procedures used to determine velocity models from dispersion measurements utilize trial and error procedures or application of partial derivatives of phase and group velocity with respect to model parameters combined with linear inverse theory. The observed surface wave data emphasize that there are pronounced lateral variations in crustal and upper mantle structure and the continents and oceans are themselves inhomogeneous. Shield areas possess the highest values of shear wave velocities with depth and a relatively weak mantle low‐velocity zone. On the other hand, rift areas have much lower shear velocities and a very pronounced low‐velocity zone. Under the oceans the lid overlying the low‐velocity zone is variable in thickness and thickens with the increasing age of the ocean floor. The average velocity above 170–200 km is less under oceans than under continents. Surface waves propagating over oceanic paths are attenuated more than continental paths, but detailed regional studie