Motor vehicle crashes (MVC) are the leading cause of death from severe injuries on the Pine Ridge Indian Reservation (PRIR), averaging 16 MVC deaths per year from 2002 to 2011. The Sacred Cargo Coalition was established in PRIR in 2007 to implement intervention strategies to increase seat belt usage and reduce MVC fatalities, including seat belt law enforcement, creating a traffic court system, and educational campaigns on MVC prevention. The study described in this article examined the effectiveness of the interventions on increasing the seat belt usage rates and reducing MVC deaths. Secondary data were collected from the National Highway Traffic Safety Administration and other federal and local agencies. Seat belt usage rates increased an average of 6.8 percentage points from 2007 (10%) to 2012 (44%). MVC fatalities decreased by 46.7% from the preintervention to the intervention period. Maintenance and improvement of the intervention strategies may be achieved by seeking additional funding and including appropriate engineering activities in PRIR.