Investigations of parameters that affect the dynamic properties of geotechnical materials are regularly performed in the laboratory. For municipal solid waste (MSW), dynamic laboratory studies are only beginning to be performed. Parametric studies of both materials are rarely, if ever, performed in the field. In the past decade, field methods have been developed with which parametric investigations can be conducted. The field methods involve applying staged, static and dynamic loads at the ground surface using footings or load plates as a surface platen. Horizontal dynamic loading to the platen creates a seismic source that generates downward propagating, horizontally polarized shear waves. Embedded arrays of small sensors in the loaded material beneath the surface platen are used to monitor linear and nonlinear shear wave propagation. The field test methods, associated equipment, and testing procedures are described. Field studies of the effects of stress state, strain amplitude and pore pressure generation on shear moduli are presented. Three types of material are investigated: (1) an unsaturated sand, (2) a municipal solid waste, and (3) a saturated, liquefiable silty sand. Shear strains in the range of about 0.0002 to 0.2% were generated in these tests.