The proposed research will include adolescent and young adult Hispanic/Latino men who have sex with men (MSM) and heterosexual men and women, aged 13-24 years, and will be based at 13 ATN Adolescent Medicine Trial Units (AMTUs) that provide clinical care and psychosocial services to the target group. In 10 of the 13 sites, comparisons will be made between alternative venue-based testing (AVT) and social and sexual network-based interviewing and HIV testing (SSNIT) strategies to assess which, among these approaches, is the most effective means for identifying undiagnosed human immunodeficiency virus (HIV) in young, at-risk Hispanics/Latinos. Three of the sites will focus solely on use of SSNIT for identifying undiagnosed HIV in our target group of adolescents and young adults. All study participants will complete an audio computer-assisted self-interview (ACASI) and undergo HIV screening. Participants with presumptive HIV positive screening results will be referred to the local AMTU for confirmatory testing, post-test counseling and referrals for linkage to HIV medical care. Linkage to care for ATN 096 study participants will be conducted in accordance with the Strategic Multisite Initiative for the Identification, Linkage, and Engagement in Care of Youth with Undiagnosed HIV Infection (SMILE in CARING for YOUTH) Program (ATN 093), a collaboration of the CDC and NICHD/ATN, to ensure that youth who test positive for HIV as part of this protocol are linked with treatment and care.