Youth suicide clusters may be exacerbated by suicide contagion-the spread of suicidal behaviors. Factors promoting suicide contagion are poorly understood, particularly in the advent of social media. Using cross-sectional data from an ongoing youth suicide cluster in Ohio, this study examines associations between suicide cluster-related social media and suicidal behaviors.We surveyed 7th- to 12th-grade students in northeastern Ohio during a 2017-2018 suicide cluster to assess the prevalence of suicidal ideation (SI), suicide attempts (SAs), and associations with potential contagion-promoting factors such as suicide cluster-related social media, vigils, memorials, news articles, and watching the Netflix series 13 Reasons Why before or during the cluster. Generalized estimating equations examined associations between potential contagion-promoting factors and SI/SA, adjusting for nonmodifiable risk factors. Subgroup analyses examined whether associations between cluster-related factors and SI/SA during the cluster varied by previous history of SI/SA.Among participating students, 9.0% (876/9,733) reported SI and 4.9% attempted suicide (481/9,733) during the suicide cluster. Among students who posted suicide cluster-related content to social media, 22.9% (267/1,167) reported SI and 15.0% (175/1,167) attempted suicide during the suicide cluster. Posting suicide cluster-related content was associated with both SI (adjusted odds ratio 1.7, 95% confidence interval 1.4-2.0) and SA during the cluster (adjusted odds ratio 1.7, 95% confidence interval 1.2-2.5). In subgroup analyses, seeing suicide cluster-related posts was uniquely associated with increased odds of SI and SA during the cluster among students with no previous history of SI/SA.Exposure to suicide cluster-related social media is associated with both SI and SA during a suicide cluster. Suicide interventions could benefit from efforts to mitigate potential negative effects of social media and promote prevention messages.