BACKGROUND: Health misinformation negatively impacts our informed health awareness, decision-making, and adherence to public health measures (Surgeon General, 2021). Consequently, San Diego County, California, declared health misinformation a public health crisis. Libraries in our region can support the County’s campaign to counteract health misinformation through information literacy support and resource access. GOAL: We aim to develop an online outreach toolkit that helps San Diego County library workers (public, academic, and school) launch an online campaign to mitigate health misinformation and engage community members for health information literacy. The toolkit provides online micro-learning content for different social media and online channels. Since health misinformation may spread quickly on the internet, we focus on online outreach to raise awareness of health misinformation and teach techniques for evaluating health claims, finding reliable sources, and responding to misinformation ethically. ACTIVITIES: This work is supported by and conducted by members of the San Diego Health Information Partnership – a collaborative team of library workers led by San Diego Circuit, a consortium of six public and academic libraries across San Diego County. We will develop images, infographics, social media message templates, video, and learning objects for the online outreach toolkit. Materials will be available in English and Spanish. The outreach materials will promote awareness of health misinformation risks and teach management skills. Afterward, we will encourage the adoption of the toolkit among library workers in the San Diego County region and provide guidance on best practices for launching an online promotional campaign. An essential outreach component is promoting NLM resources (MedlinePlus, PubMed, and ClinicalTrials.gov) to help community members find reliable consumer health and scientific sources. INTENDED OUTCOMES: Through this outreach toolkit, libraries in the San Diego County region can launch an online campaign to mitigate health misinformation. The campaign will raise awareness of health misinformation and teach community members how to respond safely. We will share the outreach materials for adaptation and reuse with libraries nationally.