The National Highway Traffic Safety Administration (NHTSA) seeks to update its evidence-based traffic safety guides: the 13th and 14th editions of *Countermeasures That Work* and the 2nd edition of *Countermeasures at Work*. The contractor will conduct literature searches, review and synthesize research, prepare chapter write-ups, and update the companion website. This procurement supports NHTSA’s Office of Behavioral Safety Research in providing guidance to State Highway Safety Offices. No specific budget amount, performance location, or submission timelines are indicated in the description. The work builds on prior editions previously developed under contract with the University of North Carolina at Chapel Hill.