DESCRIPTION (provided by applicant): This study will test the efficacy of a social network-based HIV intervention designed to increase the number of men who have sex with men (MSM) who use drugs across Kazakhstan into the continuum of care. From the start of the HIV/AIDS pandemic, MSM have been disproportionately affected-both in terms of morbidity and mortality-by HIV/AIDS. Success against HIV in general has progressed to the point where "getting to zero" new HIV infections entered the public discourse. Whereas HIV infection rates have been decreasing over the last decade for key affected populations globally, we have witnessed increasing infection among MSM, a so-called "re-emergent epidemic" for MSM. Kazakhstan is one of the few countries that saw a >25% HIV incidence increase in the 2000s and had the largest increase in rate of new infections among countries in the region. A recent study estimated HIV prevalence among MSM in Almaty to be 20.2%, a rate which exceeds HIV prevalence among adults in Sub-Saharan Africa and the most vulnerable populations in the U.S. HIV transmission in the region is driven largely by illicit drug use, and for MSM, this includes both injecting and non-injecting drug use. Kazakhstan has also been noted as lagging in ART coverage as well as adherence, especially for key populations that are vulnerable and marginalized such as MSM. Building upon the resourcefulness and strengths of MSM community members operating in a sociopolitical repressive environment, combined with the investigative team's success in adapting and pilot testing the evidence-based SHIELD social network intervention for outreach and recruitment with MSM in HIV research in the U.S. and Kazakhstan-a social network-based HIV intervention has promise to increase seek, test, treat, and retain-related behaviors. The proposed study involves a stepped wedge clinical trial across 4 cities in Kazakhstan with 1,000-1,400 drug-involved MSM to test the efficacy of the social network-based intervention for increasing the following outcomes among drug-involved MSM in Kazakhstan: (1) proportion of participants visiting a service provider to get tested for HIV; (2) proportion of HIV-infected participants initiating HIV-related care; (3) proportion of HIV-infected participants receiving ART; and (4) proportion of HIV-infected participants achieving 90% adherence to ART. In addition, the study will examine the intervention's effect on increasing use of services that address issues that co-occur with HIV, including drug abuse, HCV infection, and other sexually transmitted infections (STIs). The study has a secondary, exploratory aim designed to facilitate insight into social context (e.g., experienced stigma, social network attributes) and structural factors (e.g., number and density of services) that may moderate the impact of the intervention.