Schema summarizing outcomes associated with Chlamydia trachomatis genital tract infection control programs. These outcomes include increased number of chlamydial cases, increased rates of chlamydial reinfection, decreased detection of chlamydial-specific serum antibodies, and decreased rates of pelvic inflammatory disease, ectopic pregnancy, and tubal factor infertility. Although no causality between these observed outcomes has been established, chlamydial vaccine development will require better delineation of the linkage between enhanced early treatment and diminished antichlamydial humoral immunity, increased susceptibility to infection, and lower incidences of adverse reproductive tract sequelae.