The objective of this study was to perform a dynamic biomechanical analysis of neck collars in order to determine their effect on neck loading. A total of 32 tests were performed comparing the Cowboy Collar, Bullock Collar, and Kerr Collar. A control and each collar were tested at two speeds (5 m/s and 7 m/s), two impact locations (front and side of the helmet), and two shoulder pad positions (normal and raised). A 50th percentile male Hybrid III dummy was equipped with a helmet, shoulder pads, and the various neck collars mentioned. The helmet was struck with a pneumatic linear impactor. With the front impact location, the Kerr Collar greatly reduced lower neck force (27% reduction) and upper neck moment (43% reduction). The Cowboy Collar had a much smaller effect (<10% reduction) on neck loads. The Bullock Collar had a minimal effect on neck loads. With the side impact location, the Kerr Collar was capable of reducing lower neck moment by 18%. Although the collars had some effect on an impact to the side of the helmet, no collar greatly reduced any other neck load. These reductions in loads correlate with the degree to which each collar restricted motion of the head and neck. By restricting the range of motion of the neck and redistributing load to the shoulders, neck loads can be effectively lowered. To investigate the differences in results that using a different dummy may present, the same methodology was used comparing the Hybrid III and THOR-NT 50th percentile male dummies. 24 matched tests with were performed with the Hybrid III and THORNT. The dummies exhibited the same trends, in that either a load was reduced or increased;​ however, each load was affected to a different degree.