Project Summary Suicidality in children is a pressing and understudied public health concern. Rates of suicide in youth have tripled in recent years, yet little is known about the early emergence or development of suicidal ideation and behaviors (SI/SB). Suicidal ideation (e.g., wishing to be dead, expressing desire to kill oneself) and behaviors (e.g., choking oneself) have been identified as early as the preschool period in the context of early-onset depression. However, if and how suicidality presents in non-depressed young children is unknown. Importantly, early suicidality remains stable into school-age and confers risk for later psychopathology, suggesting lasting impact and continuity of this early manifestation. Consistent with the NIMH Strategic Objective 2, to “chart mental illness trajectories to determine when, where, and how to intervene,” the overarching aim of this K01 application is to understand the developmental contexts in which suicidality emerges in order to identify at-risk youth and to inform preventative intervention efforts. The proposed study will address a number of questions central to understanding the development of suicidality in early childhood including how SI/SB is expressed at this early age, the normative development of the understanding of suicide, if children with SI/SB exhibit lack of optimism and/or pessimism, and how children with SI/SB process peer acceptance and rejection. A variety of measures, including child interview and narrative approaches, behavioral tasks, and event related potentials (ERPs) will be administered to three groups of 4- to 7-year-olds from diverse racial and socioeconomic backgrounds: 1) children with a history of SI/SB, 2) children with or at risk for psychopathology but no history of SI/SB, and 3) low-risk healthy children. The inclusion of children with or at risk for psychopathology with no history of SI/SB will address the specificity of risk factors for suicidality relative to depressive symptoms and other forms of psychopathology. This approach has the potential to identify transdiagnostic risk-factors of suicidality in young children. The inclusion of low-risk healthy children will inform our understanding of typical and atypical trajectories of suicide understanding and provide guidance regarding how and when to address expressions of suicidality in childhood as a clinical concern. This will be the first study of children this young with SI/SB to be targeted for a study designed to investigate the developmental antecedents of risk and resilience for SI/SB. Suicide research and prevention is a high priority research area for NIMH and the described research and training activities will enable the candidate to develop an independent research program that addresses the rising rates of childhood suicidality. Specifically, the execution of the proposed project will provide the candidate with training and expertise in suicide research and prevention, child psychopathology, and ERP...