Background: This study examined the acceptability and feasibility of using a biological outcome measure to evaluate a school-based sexuality education program. Confidential field-delivered sexually transmitted infection (STI) testing by nonmedical field staff and STI treatment by medically trained field staff was assessed in off-campus and off-clinic settings for adolescents enrolled in the trial. Methods: After parental and adolescent consent were obtained, a convenient time and location was identified to collect urine to test for chlamydia ("Chlamydia trachomatis," CT), gonorrhea ("Neisseria gonorrheae," NG), and trichomonas ("Trichomonas vaginalis," TV) infection and to treat students with positive results. Results: A total of 391 of 1742 students had permission to participate (22%); 353 (90%) provided urine samples; 28 (8%) had positive test results: CT(18), NG(5), and TV(8). Testing and treatment occurred at home for 92% and 59% of students, respectively; on weekdays (for 69% and 96%, respectively) and between noon and 8 pm (for 76% and 88%, respectively). All students who tested positive were treated. Several lessons and strategies that may improve the likelihood that students will participate in field-delivered STI testing and treatment emerged. Conclusion: STI testing and treatment are feasible for students enrolled in a school-based sexuality education program. However, obtaining parental consent may be challenging.