Prevention Ambassadors: Intervention to Promote HIV Service Engagement in the Networks of SSP Clients

Index Participant Inclusion Criteria: * Being greater than or equal to 18 years old * Reporting drug use (past month) * Having other people who use drugs (PWUD) in one's social network * Being willing to talk about HIV testing and services with at least 2 PWUD in their networks and attempt to refer them to the study * Speaking English fluently Peer-Recruit Participant Inclusion Criteria: * Being greater than or equal to 18 years old * Reporting drug use (past 3 months) * Being recruited by an index participant (evidenced by presenting the coupon used to recruit them) * Speaking English fluently Exclusion Criteria: \- Persons who participated in formative study activities related to the development of the PA intervention will not be eligible to participate.