Objective: Despite evidence-based interventions for the psychiatric disorders that often precede suicidality, suicide remains a leading cause of death among youth. There has been increased interest in whether preventive interventions targeting early risk factors lead to decreased distal risk for suicidal thoughts and behaviors (STB). We examined the impact of Coping Power (CP), a school-based preventive intervention targeting externalizing problems on STBs. Method: The sample included 3,182 youth (36.4% female youth; 77.3% Black youth) who participated in one of 11 randomized controlled trials of CP. Individual-level data across trials were harmonized using integrative data analysis to address cross-study variation in STB measurement. The study used meta-analysis of individual participant data for modeling cross-study variation in intervention effects, and propensity score weighting for addressing covariate imbalance arising from combining intervention arms across studies. Hypothesis tests were conducted for parent- and teacher-reported STBs under propensity score-weighted multilevel modeling. Results: Compared to school-as-usual, youth participating in Mindfulness-Enhanced CP demonstrated significant decreases in parent-reported STBs over time (b = -0.08 (0.02), p < 0.001, after one year: d = -0.13, after two years: d = -0.25), and youth participating in Internet-Enhanced CP demonstrated significant decreases in teacher-reported STBs over time (b = -0.08 (0.03), p =0.003, after one year: d = -0.20, after two years: d = -0.40). Inconsistent results for Standard CP and Individual CP in sensitivity analyses preclude clear conclusions for these two intervention formats. Conclusion: Our synthesis of findings highlights the promise of digital health and mindfulness-based interventions for youth with externalizing problems in reducing STBs. Additional research is needed to better understand the nature of "for whom," "how," and "under what conditions" preventive interventions impact later STB. [This paper will be published in "JAACAP Open."]