The workshop on vapor intrusion into indoor air from contaminated groundwater was sponsored by SERDP and ESTCP and held in Tempe, Arizona on December 19, 2013. The goal of the workshop was to develop a path forward for investments and technology transfer by SERDP and ESTCP in vapor intrusion assessment. Specific questions addressed included (1) what additional research is warranted in this area, if any? (2) Are there additional technology or methodology demonstrations needed to move the field forward to implementation of key concepts? (3) What interactions need to take place with the end users? and (4) Are additional guidance documents, training, and/or seminars needed? The workshop's agenda focused on the research needed to deal more efficiently with the characterization and mitigation of sites impacted by contaminant vapor intrusion, with overall objectives to (1) review the current status of SERDP and ESTCP's funded efforts on vapor intrusion, and (2) discuss future research and demonstration needs to improve our ability to properly assess the vapor intrusion pathway and indoor air concentrations. Approximately 25 invited experts representing DoD remedial program managers, state regulators, engineers, academic researchers, and consultants attended the workshop. A review of the research, demonstration, and technology transfer needs identified is presented in the Workshop Report.