We are all well-versed in several geophysical methods, equipment, and data reduction techniques useful in geotechnical exploration and evaluation. Geophysical exploration is an non-invasive tool which uses the measurement of material properties to help assess potential subsurface conditions. The field of geophysical exploration has grown substantially over the past 30 years, and has earned a good reputation as a relatively cost-effective, non-invasive tool to help supplement traditional subsurface exploration techniques and/or provide stand-alone subsurface information. Despite their obvious benefits, geophysical exploration techniques should not be viewed as an equal alternative to standard subsurface exploration and careful planning should be used at the beginning of a project to determine what the most appropriate exploration technique/method may be given the assumed subsurface conditions. Geophysical exploration will not always be appropriate for a given project.