Background: Adolescents' worry (perceived threat) of sexually transmitted diseases (STDs) and HIV infection may have different correlates. This study examined associations between selected psychosocial and behavioral constructs and adolescents' worry about STD and HIV infection. Goal: To assess levels and correlates of worry about STD and HIV among a high-risk sample of black adolescent females. Study Design: High-risk black females (n = 522), enrolled in a randomized, controlled HIV and STD prevention trial, completed a questionnaire and structured interview at baseline. Worry about STD and HIV infection, recent risk behaviors, and several measures potentially related to worry were assessed. Results: Levels of worry for both STD and HIV were low. Recent history of STD infection was associated with STD worry (OR, 4.6) and HIV worry (OR, 2.0). Infrequent communication about sex (OR, 2.0) and low perceived ability to negotiate condom use (OR, 2.0) were related to STD worry; whereas, only partner-specific barriers were related to HIV worry (OR, 1.9). Conclusions: Despite high risk, adolescents were generally complacent about the threat of infection with STD and HIV. Adolescents' worry about STD and HIV infection had different sets of correlates.