The objective of the proposed project is to develop and test a theoretical model of the relationship between conflict and human immunodeficiency virus (HIV) and related diseases (e.g. tuberculosis) among World Health Organization Member States. The model defines the direct effects of conflict on HIV, and the indirect effects of conflit on HIV spread operating through two sets of indicators; background susceptibility factors (e.g. baseline prevalence of HIV) and vulnerability factors (e.g. substance use) that reflect changes induced by conflict. In this explanatory model, susceptibility and vulnerability factors are hypothesized to serve as moderators and mediators of the conflict-HIV relationship. One vulnerability factor of central interest is substance use including alcohol use, non-injection illiit drug use and especially injection drug use (IDU). Consideration of IDU in explaining the conflict-HIV relationship is important given that IDU accounts for about 10% of the estimated 27 million new HIV infections that occur each year and for 30% of these new infections occurring outside Sub-Saharan Africa. Research attention has focused on the relationship between IDU and HIV, Hepatitis B virus, Hepatitis C virus, and sexually transmitted infections (STIs), tending to overshadow the importance of these diseases associated with non-injection drug use and alcohol use. The proposed project also aims to: (1) identify new and refine existing indicators of susceptibility and vulnerability; (2) examine hypothesized direct and indirect effects of conflict n HIV among relevant subgroups in which the relationship may differ (e.g. Sub-Saharan African vs. Non-Sub-Saharan African countries); and (3) test alternative explanatory models using structural equation modeling. These objectives and aims will be supported by a research training plan that involves learning/enhancing knowledge of advanced epidemiology, biostatistics and HIV and related infectious diseases and global health and training in presentation skills, conduct of research, manuscript writing and preparation of fundable grant proposals, mentoring and receiving training in the responsible conduct of research. This project is of substantial relevance to the research priorities of the National Institute on Drug Abuse, tha is, its focus on prevention and treatment of HIV, including developing intervention strategies, addressing HIV/AIDS, understanding IDU epidemics in different geographic areas, assessing the role of immigration/migration on HIV transmission and research addressing the epidemiology of HIV/AIDS and related co-infections and other STIs and tuberculosis, epidemiology, and behavioral, social and economic determinants of HIV/AIDS.