Whiplash associated disorders (WAD) resulting from rear end car impacts are an increasing problem. WAD are usually not life threatening, but are one of the most important injury categories with regard to long-term consequences. This paper is a review of Volvo's Whiplash Protection Study (WHIPS), which is the result of more than ten years of concentrated research efforts in the area of neck injuries in car collisions, with the focus on rear end car impacts. The study follows the whole chain from accident research to the development of a seat for increased protection against WAD. Results from Volvo's accident research are summarized. Existing biomechanical knowledge regarding possible injury mechanisms are presented and discussed. Based on the interpretation of accident research and biomechanical knowledge, guidelines for improved protection against WAD in rear end impacts are presented. Requirements and test methods based on the guidelines are explained. An important part of the study is a new rear end impact dummy, BioRID. Test results using the new dummy are presented. Finally, the paper explains the design of a new seat for increased WAD protection, the WHIPS-seat. Results from the accident research and biomechanical research emphasize the importance of considering the whole spine of the occupant and, accordingly, the whole seat when addressing WAD in rear end impacts, with a particular focus on low and moderate impact severity. Low and moderate impact severity crashes should be focused. Also important to consider are the individual differences between occupants, the seating position and the variety of seating postures. All results, including sub-system testing, mathematical modeling, sled testing, as well as geometrical parameters show that the WHIPS-seat will have considerable potential for offering increased protection against WAD in rear end impacts.