Abstract / Summary Firearm-related injuries recently became the leading cause of death among children in the U.S., and children under 5 years of age are among the largest age groups of all ages impacted by unintentional firearm injury. Thirty-four percent of gun deaths among children under age 5 were unintentional, compared with less than 2% of adults ages 20 and over.3 We posit that current approaches fail to prevent unintentional firearm injury and mortality in early childhood for 3 key reasons: 1) mismatch in parents’ mental models of firearm risk and injury prevention compared to expert recommendations; 2) barriers to safe firearm practices specific to the early childhood period; and 3) need for precision messaging that addresses these issues and is delivered by trusted messengers. The purpose of the proposed study is to address these gaps by engaging parents of young children (ages 0 to 5 years) with a mixed-method, community-based approach for intervention development and pilot implementation. Specifically, in response to NOFO RFA-CE-23-005 to inform firearm-related violence and injury prevention strategies (funding option B), our Aims are to: First, conduct focus groups and interviews with parents and experts and a national survey to better understand parents’ mental models and identify areas of mismatch with expert views regarding firearm safety practices (including safe storage behavior and communication with others in the child’s environment). We will use both quantitative and qualitative data to examine and refine a theory-informed conceptual model of parent firearm safety practices and identify modifiable factors related to parent mental models of firearm safety in early childhood; Second, use the findings to develop effective intervention strategies, messages, and materials to address barriers to firearm safety during early childhood and promote firearm safety behavior and communication; Third, engage parents as trusted peer messengers to deliver a pilot version of the firearm safety intervention using parent- empowerment techniques. We will evaluate receptivity of messages for firearm-owning parents with young children, conduct process and outcome evaluation of the intervention using a case-control design and collect both qualitative and quantitative data from participants to inform intervention refinement. The findings from this project will inform promotion of effective firearm safety practices using a parent-empowerment model among parents with young children.