Among those that face the greatest risk for contracting Human Immunodeficiency Virus (HIV) are black adolescents between the ages of 13 and 24. Nearly one-third of new infections occur among this demographic. Among all youth, black men have higher rates of contracting HIV in comparison to any other race/ethnicity. This study focuses on the roles of the family, primarily parental communication and relationship factors, and school, primarily peers, and teachers, and how they are associated with sexual health behaviors (condom use, HIV testing, etc.); their impact, in short, on shaping health behaviors. This dissertation study examines the following questions among Black adolescent males: (1) Are there mediational relationships between parent support, self-efficacy beliefs about sex, sense of belonging at school, parent relationships, parent attitudes about sex, peer knowledge, racial discrimination, and HIV sexual risk behaviors? (2) Are self-efficacy, sense of belonging, parent support, parent attitudes towards sex, parental relationships, and peer knowledge predictive of HIV testing (ages 14-26)? Using longitudinal data from the National Longitudinal Study of Adolescent to Adult Health (Add Health). Add Health is designed to explore health and social context from adolescence to adulthood (Carolina Population Center). Includes a nationally representative sample of U.S. adolescents from grades 7 through 12, over four waves (1994-95, 1996, 2001-02, 2008 ) and collects data on respondents’ social environment, family environment, behaviors and choices, physical health, education, goals and achievements. The main analytic strategy to addressing research question was a multinomial analysis and a structural equation model. The results indicated that parent support positively predicted HIV testing among Black males at waves 1 and 3. Results also indicated that parent attitudes was negatively associated with males being tested at both waves 1 and 3. These results our important because the eco-developmental theory suggests that microsystems are the most influential with respect to adolescent HIV/Sexually transmitted disease risk behaviors now extending to HIV testing.