People living with HIV infection (PLH) are clustered in friendship groups with other HIV+ persons, and an intervention delivered to all members of PLH social networks allows HIV+ people who are friends in day-to-day life to provide one another with support for entering, remaining, and adhering to HIV medical care. Moreover, an intervention delivered to groups attended by HIV+ persons who are friends increases HIV medical care engagement and decreases problem drinking more than individual counseling, probably because the network intervention harnessed mutual peer social support among friends who share the same HIV status, face similar coping issues, and interact together in day-to-day life. The planned research will be conducted in two phases in St. Petersburg, Russia.

Phase I of the planned research will be the conduct of in-depth interviews with 30 HIV+ persons not in medical care or not adherent to anti-retroviral therapy (ART) regimens, including men and women representing diverse exposure risks (drug use, men who have sex with men, and heterosexual transmission). Interviews will elicit information on ways in which HIV-positive friends can support one another in HIV care entry, retention, and adherence; types of support from PLH friends that would best support treatment engagement; and how peer supports can lessen the negative effects of substance use on care engagement.

Phase 2 will recruit 48 out-of-care or ART nonadherent HIV+ individuals from community settings in St. Petersburg, Russia. These individuals, who are referred to as "network seeds," will invite their HIV+ friends, who will in turn invite their own HIV+ friends into the study, creating a sample of 48 networks (expected n=288, 6 members/network x 48 networks). Following baseline assessment of care engagement, ART adherence, treatment attitudes, psychosocial distress, substance use, and CD4+ and viral load, 24 networks (n=144 participants) will be randomized to an intervention condition and 24 networks (n=144) to the comparison condition. All members of each intervention condition network will together attend a 4-session intervention to strengthen attitudes, intentions, and skills for entering, remaining, and adhering to HIV medical care. Because participants will attend sessions with other individuals who are their own friends in day-to-day life, the intervention will build and increase mutual social support within each network for HIV care and adherence. Peer champions identified in each intervention network will attend 3 additional sessions in which they are guided to reinforce and help to sustain friends' medical care engagement. Intervention outcomes will be determined by baseline to 6- and 12-month followup change on primary measures of participant attendance at HIV medical care visits, adherence to ART regimens, and viral load as well as secondary measures of alcohol use, drug use, sexual risk behavior, treatment attitudes, and psychosocial distress.

Inclusion Criteria:

• Age 18 or older;
• Self-report as being HIV-positive, with positive HIV status confirmed in study-provided testing;
• Except for initial seeds, must be named by an already-enrolled participant as a PLH friend; and
• Do not plan to move from the St. Petersburg, Russia, area for the next 18 months.

Exclusion Criteria:

• Age 17 or younger;
• Self-report as HIV-negative or HIV-positive serostatus is not confirmed by testing;
• Not be named as a PLH friend by an already-enrolled participant; and
• Intend to move from the St. Petersburg, Russia, area during the next 18 months.