The purpose of this research study is to test the safety of and the body's response to an experimental cytomegalovirus (CMV) vaccine (called gB/MF59 vaccine). Participants will include approximately 400 healthy females, ages 12-17, recruited from adolescent clinics at Cincinnati Children's Hospital Medical Center, Vanderbilt University Medical Center, Baylor College of Medicine, University of Texas School of Public Health, Houston, and the University of Texas Medical Branch at Galveston. Participants will receive 3 doses of vaccine or placebo (saltwater) on a 0, 1, and 6 month schedule. Study procedures will include blood and urine samples. Participants will complete a diary recording temperatures and any side effects experienced. Subjects will be involved in study related procedures for up to 31 months.