PROJECT SUMMARY Suicidal thoughts and behaviors (STBs) are the 5th leading cause of death among young children and non-fatal STBs account to close to half of emergency room visits in this age group. There is a dearth of research examining STBs among pre-adolescent children and a critical need for validated screening tools to identify children in need of intervention. Existing STB research tends to exclude individuals from marginalized backgrounds further limiting the generalizability of already sparse research in this population. Improving suicide prevention in children requires research innovation for this vulnerable group. There are three particularly critical barriers to identifying children at risk of STBs: 1) parental fears that STB assessment is iatrogenic; 2) lack of developmentally appropriate tools and methods for identifying child risk; and 3) lack of culturally appropriate and valid tools to address parent concerns and to identify child risk. This supplement in response to NOT-MH-22-195 directly addresses these barriers to identifying STBs in young children by leveraging an existing cohort of socioculturally and economically diverse mothers and their 5- to 8-year-old children, followed intensively from before birth with comprehensive assessments of cognitive and emotional development supported by a NIMH Conte Center grant (P50 MH096889). Incorporating critical community perspectives, this supplement tests the following aims: 1. Provide developmentally and culturally appropriate methods for assessing and quantifying STBs in 5- to 8-year- old children; 2. Test the efficacy of a brief informational intervention to increase parent consent to probe STBs in 5- to 8-year-old children; 3. Validate/implement novel instruments for STB assessment capitalizing on a thoroughly characterized and culturally diverse cohort. The discoveries generated by this project address critical gaps in the development of tools to accurately assess STBs in young children in need of life saving intervention. Further, the proposed supplement falls within, and enriches, the scope of the parent grant. The parent grant investigates early origins of anhedonia and as STBs often accompany or follow anhedonia, this supplement provides an important complementary outcome measure. Additionally, the parent grant probes the role of unpredictable early life experiences in psychopathology and Aim 3 of the supplement enables assessment of the role of unpredictability in STBs. The present study has the potential to transform the study of STBs in children, by enhancing parent consent to assessment of STBs and increasing confidence in the validity of STB assessment in children.