This technical assistance report investigated the existing state of practice across the nation for placing safety campaign messages on dynamic message signs (DMS) and reviewed relevant studies that documented any evidence of effectiveness in influencing driver behavior and providing a public safety benefit. The number of state transportation agencies posting safety messages on DMS has increased over the last few years and messages are typically focused on common dangerous behaviors such as drowsiness, distractions, aggression, alcohol or drug impairment, and unrestrained driving. Several states have started to display their state-specific number of traffic fatalities year-to-date on DMS. Several studies showed that there could be changes in driver behavior by posting safety messages on DMS; some also included small samples of traffic data analysis, which showed some speed changes when the drivers approached active DMS. Overall, the findings from this report support the use of DMS to disseminate highway safety messages. However, more research is needed to validate the perceptions noted in the surveys and more field studies are necessary to confirm long-term impacts of using DMS to convey safety messages about driver behavior and traffic safety.