Background. Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen in the United States and disproportionately affects African-American adolescents. The objectives of this study are to determine the prevalence of C. trachomatis and to identify correlates of infection among African-American adolescent females. Methods. Sexually active African-American adolescent females (n = 522) completed a self-administered survey and structured interview and provided vaginal swab specimens for laboratory assessment of STDs. The relationship among selected psychosocial, behavioral, and biologically confirmed STDs and C. trachomatis was assessed. Results. The prevalence of C. trachomatis was 17.4%. Results of multiple logistic regression revealed that adolescents testing positive for C. trachomatis infection were significantly more likely to test positive for gonorrhea (OR = 5.0; 95% confidence interval (CI) 1.69-14.83); to report nonuse of condoms with a steady partner (OR = 2.4; 95% CI 1.23-4.76); to be in shorter relationships (OR = 2.2, 95% CI 1.13-4.30); and to perceive less parental monitoring (OR = 2.1; 95% CI 1.08-4.15). Conclusions. Study findings emphasize the need for assessing psychosocial factors, behavioral factors, and the presence of other STDs when determining risk for C. trachomatis. Several of the constructs identified are particularly amenable to behavioral interventions designed to prevent infection. © 2002 American Health Foundation and Elsevier Science (USA).