Project Summary/Abstract Suicide is a leading cause of death in the US with an estimated 46,000 suicide deaths occuring in 2020. Loneliness, an interpersonal risk factor for suicide, was recognized as having reached epidemic proportions by the US Surgeon General in 2017 before rates further worsened due to the COVID-19 pandemic. Given the public health impact of loneliness, the National Academies of Engineering, Sciences, and Medicine have called for health systems to take an active role and intervene to reduce loneliness. Primary care is the optimal health system setting to deliver loneliness interventions to prevent suicide because primary care increasingly screens for loneliness along with other social determinants of health. Primary care practices also increasingly employ behavioral health care managers who can deliver loneliness interventions along with treatments for depression and anxiety disorders that may impair recovery from chronic loneliness and contribute to suicide risk. Prior primary care approaches to loneliness have had mixed results and there remains no established, effective, ready-to-adopt model to reduce loneliness and suicidal ideation in primary care. This study will adapt two loneliness interventions, social prescribing and brief cognitive therapy, to be delivered within primary care. Social prescribing addresses the structural determinants of loneliness (i.e., breadth and frequency of social interactions) by linking patients to community-based organizations or activities (e.g., volunteering) whereas brief cognitive therapy addresses the cognitive determinants of loneliness (i.e., relationship expectations) through education, reflections, and guided exercises. In contrast to prior studies, both interventions will be adapted to be delivered by a behavioral health care manager working within a primary care-based collaborative care management program. The specific aims of the project are: 1) Adapt social prescribing and brief cognitive therapy interventions for loneliness to be delivered as components of primary care collaborative care management and 2) conduct a randomized controlled pilot study (N=60) to determine feasibility and acceptability of the two interventions and trial protocols. The Aim 1 development activities will be guided by the ADAPT-ITT (assessment, decision, administration, production, topical experts, integration, training, testing) framework and will engage patient and provider stakeholders to inform production of manuals to guide training and pilot testing of the interventions. In the Aim 2 pilot study, patients from two primary care sites who screen positive for loneliness and suicidal ideation will be randomly assigned to one of the two interventions or to EUC. At 3 months, participants in the intervention arms will receive the alternate intervention for an additional 3 months, and EUC participants will continue to receive EUC. Feasibility and acceptability will be measured to inform a future adequatel...