PROJECT SUMMARY/ABSTRACT Today's sexual and gender minority (SGM) youth are coming out at increasingly younger ages, with the average age of disclosure at 13 years old and 35% coming out as preteens. SGM preteens experience up to 14 times higher risk for suicidal thoughts and behaviors (STBs) compared with their heterosexual, cisgender peers. SGM preteens' social and developmental contexts likely contribute to significant risk and protective factors for STBs. For example, they must simultaneously navigate preteen developmental stressors and supports (like peer relationships and first romantic experiences) while also managing an emerging SGM identity and associated exposure to stigma-related stress and resilience. Yet, several knowledge gaps remain. The field of SGM preteen research is in its infancy, without consensus on best practices for sampling and recruiting high-risk SGM preteens. The field also lacks psychometrically valid assessments for SGM preteens as well as longitudinal studies assessing risk and resilience trajectories during this sensitive developmental period. The overarching goal of this rigorous multi-method project is to address these gaps. Youth and parent advisory boards will be assembled to enrich our research and ensure its cultural responsiveness, ethical soundness, and ultimate benefit to SGM preteens and families. Our research will address three aims. First, we will use a five-step Delphi process to develop consensus among a diverse panel of experts (including researchers, clinicians, legal experts, parents, leaders of SGM community youth groups) on best practices for safely, ethically, and effectively sampling, recruiting, and retaining SGM preteens at risk for suicide into research. Second, we will create and pretest an assessment of stigma-related stress and resilience for SGM preteens using a three-phase approach (developing an initial item pool; refining items; establishing content validity with SGM preteens). Last, we will enroll a national cohort of 120 SGM preteens at risk for suicide with one parent/caregiver, which we will call the SPARK (SGM Preteens Advancing ouR Knowledge) Cohort. SPARK participants will be administered an online assessment battery of developmental stressors and supports, stigma-related stress and resilience, and STBs every 6 months for 2 years. Analyses will use rigorous weighted generalized estimating equations to estimate trajectories of risk and protective factors for STBs. Subgroup analyses will further examine how trajectories of STBs and associated risk and protective factors differ by race and ethnicity, gender identity, and other theoretically informed intersectional factors among SGM preteens. This research is guided by an innovative conceptual model integrating advances in developmental science with the NIMHD SGM Health Disparities Framework and involves community partners at SGM youth organizations nationwide to enhance feasibility. Findings from this project will advance best pra...