The Ambulance Patient Compartment Human Factors Design Guidebook, hereafter referred to as the Guidebook, is the result of a multiyear effort on the part of the U.S. Department of Homeland Security (DHS) Science and Technology Directorate (S&T). It is intended to provide tools and guidance to the Emergency Medical Services (EMS) community that will enable the design and manufacture of ambulance patient compartments that are safer and more efficient. S&T received support in the development of the Guidebook through collaboration between the National Institute of Standards and Technology (NIST), the National Institute for Occupational Safety and Health (NIOSH), BMT Designers and Planners (D&P), and Carlow International as well as input from members of the EMS community representing both EMS providers (EMSP) and manufacturers.