The United States is facing unprecedented rates of drug overdose deaths, profoundly impacting millions of families who are left to navigate their grief. Those bereaved by overdose experience a unique form of grief characterized by feelings of guilt, shame, and blame, which can worsen their suffering and deter them from seeking help. Individuals coping with overdose loss often endure more severe health consequences compared to those grieving non-drug related deaths, including prolonged grief disorder, substance use disorders, PTSD, depression, and suicidal thoughts. Moreover, bereaved individuals, particularly those with a history of substance use, may engage in risky behaviors as a means of coping, further exacerbating the risk of overdose and mortality within this vulnerable population. Peer grief support interventions have emerged as a promising approach to assist those experiencing such losses. To combat these outcomes, we are collaborating with Peer Community Support Partners (PSCP) in a novel practice-research partnership to implement the RIVER peer grief support model. Though RIVER has shown success in community settings, it has yet to be rigorously evaluated. In a three-aim approach, this study aims to assess the effectiveness of the RIVER model while also enhancing and engaging grievers with support resources via medical examiner offices (MEOs), which routinely contact families during death investigations. This research represents a pivotal advancement in addressing the needs of the overlooked bereaved community, aligning with the NIH's Helping to End Addiction Long-term (HEAL) initiative to develop effective strategies against the opioid crisis. Together, community engagement and rigorous research efforts aim to enhance support for those affected by the tragedy of drug overdose.