Rates of suicide among the young have been rising globally for decades. Despite research advances, suicide is now the second leading cause of death worldwide for those 15-29, clearly a global public health crisis. Importantly, improved prevention and intervention depend on development of innovative research approaches that overcome the challenges of existing research and that can lead to a broader and deeper understanding of the yet unidentified risk factors. We call these “invisible risks”. As LMICs represent 80% of the worldwide suicides, they are an important target for suicide prevention efforts. The risk factors for youth suicide in LMICs are especially poorly understood, in part due to the logistics of conducting epidemiologic research in LMICs, and in part because suicide research has its own well-known challenges, regardless of where it’s conducted. This proposed study of youth suicide, including its trajectories and risk factors, will take advantage of the special circumstances of Guyana, the country with the second highest rate of both adult and youth suicides in the world, and a Ministry of Health committed to suicide prevention and actively cooperating with our team to investigate adult suicide. Guyana has notable heterogeneity in ethnicity, race, religion and economic class, making it an important model country for suicide research. In addition, this proposed study will leverage the human, intellectual, and administrative infrastructure developed for our ongoing NIMH funded Guyana Well- Being Study. Taken together these factors make Guyana a well-suited site for the goals of this study, including examining factors that have often been ignored or misclassified, for example when youth present to the ERs with injury, accidents, or other clinical presentations, that may actually have an invisible suicide component. The goals of this study will be realized through three different youth cohorts: 1) A nationally representative Community Sample ages 10-24 (N=5000), will be thoroughly assessed to determine prevalence of a range of suicidal behaviors (ideation, attempt and completion) and the presence of risk factors, using a unique blend of quantitative and qualitative (vignettes) measures. This Cohort will also serve as comparisons/controls for the other two Cohorts. 2) The Clinical Attempters Sample will include all identified suicide attempters (estimated N=400), who will be assessed and compared to the Community and ER samples in a case-control design, to uncover factors influencing trajectories of suicidal behaviors. 3) Emergency Room Sample: To uncover an additional source of “invisible” risk factors, we will screen youth who present at the ER for ostensibly non-suicidal reasons (N=720) and assess them in the same way as the Community and Attempter samples. The assessment of each Cohort will be followed longitudinally in two subsequent waves. Taken together, these Cohorts, analyzed individually, longitudinally, and in case-control com...