As HIV-positive children are surviving to adolescence and beyond, understanding their HIV knowledge and sexual behavior is critical. Forty HIV+ adolescents/young adults were interviewed twice, approximately 21 months apart (mean age 16.6 and 18.3 years, respectively). Data on demographics, safer sex knowledge, sexual risk behaviors, risk reduction self-efficacy, and Tanner stage were collected. Twenty-eight percent of HIV+ youth at Time 1 and 41% at Time 2 reported being sexually active. HIV transmission/safer sex knowledge was low, increased with age, and both self-efficacy for and actual condom use was relatively high. Secondary prevention messages should be incorporated into routine medical settings.