The investigators propose recruiting 300 HIV/HCV co-infected PWID (i.e. Index participants). Half will be randomly assigned to the experimental condition and half to the equal attention comparison. The experimental intervention will include 8 group sessions that focus on communication to social network members, medical adherence and risk reduction skills, 2 dyad sessions with network members, monthly booster sessions for 6 months, and mHealth cuing of behavior for 6 months. These Index participants will be followed for 24 months (3, 6, 12, 18, \& 24 month assessments). Participants who test positive for HCV will be linked to the Johns Hopkins Viral Hepatitis clinic to assess liver function and HCV chronicity and if applicable offered HCV treatment. Additionally, 450 network members will be recruited and will be tested for HIV and HCV and followed longitudinally to examine the social diffusion and social network factors associated with adherence among the Index participants.
