PROJECT SUMMARY American Indian (AI) youth demonstrate early initiation of substance use and subsequently high rates of substance misuse. One factor contributing to ongoing risk for these youth is the relative lack of prevention strategies that leverage contextual and cultural strengths to optimize effectiveness and sustainability. Rich cultural and traditional practices, including collateral kinship networks, make interpersonal relationships particularly vital for AI youth, but these networks are largely untapped in prevention approaches. Research in other populations demonstrates the role of social networks in both risk and resilience, but data on AI social networks is sparse and data on how networks relate to risk for early substance use virtually nonexistent. There are reasons to suspect that social network theories may require some adaptation for the culture and context of AI communities. To effectively inform interventions, we must first confirm which principles translate well and create new metrics where needed. This mixed-methods study will collect quantitative social network surveys and qualitative interviews with adolescents on a Northern Plains reservation to explore how these networks are structured and the principles under which they operate. Network characteristics will be examined in relation to substance use and related risk factors, most notably suicide and exposure to violence, to begin to understand how networks impact both risk and resilience. Network characteristics are likely to influence substance use, exposure to violence, and suicide risk in complex ways that are shared in both common and differential patterns. An explanatory sequential mixed method design (QUAN → Qual) will be used to accomplish two specific aims: Aim 1: Describe peer, kinship, and community social networks of AI adolescents. Hypothesis: Standard metrics of social networks will require modification to characterize social networks of AI adolescents; networks will have less homophily and more intergenerational and community relationships. Aim 2: Explore how social network characteristics predict risk and protective factors for substance use independently and in combination with violence and suicide. Hypothesis: Risk and protective characteristics of youth networks will be related in both common and unique ways to substance use, violence and suicidality. This project will be led by a multidisciplinary team of early stage Principal Investigators who are themselves American Indian and Alaska Native. These researchers have substantive expertise in substance use, exposure to violence and suicide among AIs, methodological expertise in community-engaged research with tribal communities, social network theory and analyses, and quantitative, qualitative, and mixed methods approaches. This project leadership team will be supported by a senior researcher with extensive experience in most of the areas relevant to this study and 18 years’ experience conducting research...