The study consists of two complementary trials, denoted as Part A and Part B. In Part A, women/girls who had a positive test for chlamydia will be enrolled when they visit the study clinics for treatment. After written informed consent is obtained, women will be randomly assigned to the Clinic Group, in which they will be advised to return to the clinic for rescreening for chlamydia, or the Home Group, in which women will be asked to collect a vaginal swab at home and mail it to the study laboratory for chlamydia testing. In part B, women who were tested and empirically treated for a chlamydial infection will be called if their tests were positive. Enrollment will be offered over the phone after verbal consent. Rescreening will be scheduled 3 months after treatment of the initial infection for women in both trials.