Abstract
Objectives. To test low-cost, scalable interventions designed to encourage seat belt use (primary outcome) and discourage handheld phone use while driving. Methods. A randomized controlled trial assigned 1139 consenting General Motors‒connected vehicle customers in the United States to 1 of 4 groups for a 10-week intervention: (1) control, (2) behavioral engagement, (3) behavioral engagement plus raffle, and (4) behavioral engagement plus shared pot. Behavioral engagement involved education, personalized tips, a "wish outcome obstacle plan" exercise, and weekly feedback about buckling and handheld-free streaks. Participants in the behavioral engagement plus raffle group also earned a chance at a $125 prize each week they had a buckling or handheld-free streak. Those in the behavioral engagement plus shared pot group earned an equal share of this prize for each streak. The intervention was delivered virtually in spring 2023. Results. Participants in the behavioral engagement plus shared pot group had a higher buckling rate (91.3%) than those in the behavioral engagement plus raffle (89.5%), behavioral engagement (89.4%), or control (88.3%) groups-differences that remained significant at follow-up. Handheld phone use did not differ significantly. Conclusions. A behavioral intervention with a shared pot incentive could be delivered at scale to reduce injuries and deaths associated with vehicular crashes. Trial Registration. ClinicalTrials.gov identifier: NCT05469477. (Am J Public Health. 2025;115(5):758-768. https://doi.org/10.2105/AJPH.2024.307980).