Cannabis use by U.S. adults has increased by 50% over the last decade, and over the same period, cannabis use by drivers has increased by an estimated 8 -12%. Cannabis impairs psychomotor functions that can impair driving ability, which in turn may increase crash risk. As a result, drug-impaired driving is a growing traffic concern. While traditional approaches have focused on enforcement and education, another approach is to build a positive traffic safety culture, which can be described as shared values and beliefs that influence safe driving decisions. Through this NHTSA-funded project, the Center for Health and Safety Culture conducted research to develop a better understanding of belief systems that predict intention to drive after using cannabis. The research included surveys of cannabis users and non-cannabis users in the state of Washington. The findings guided the development of culture-based interventions and strategies to sustainably reduce impaired driving. Sponsor: US National Highway Traffic Safety Administration Start Date: 04/15/2019 End Date: 09/30/2021 PI: Ward