This section of the issue of Geophysics is draw from a collection of papers originally submitted for a monograph on engineering and groundwater geophysics. It is a mixture of tutorial, new developments, and case histories focused on seismic methods. This introduction will review the evolution of this section and introduce each of the papers. These papers complement the overview presented by Dobecki and Romig (1985) in the Golden Anniversary Issue of Geophysics. That paper reviews the history, summarizes the state of the art, and attempts to predict possible future developments.