Long-acting reversible contraceptive (LARC) use has been increasing for almost 2 decades; however, while LARC methods are highly effective at preventing pregnancies, they do not prevent sexually transmitted infections (STIs). As a result, there is concern that the increased use of LARCs could lead to increased risk for STIs through sexual risk behaviors such as reduced condom use. Between 1 January 2015 and 31 December 2018, 18,691 service women in the study population received an intrauterine device (IUD) and 17,723 received an implant. Among active component service women who received an IUD or implant and maintained the same marital status during the study period, there was no notable increase in incidence of STIs in the 12 months after LARC insertion when compared to the 12 months before insertion. However, findings did show that rates of STIs increased from the LARC pre-insertion period to the post-insertion period among women in the youngest age category, suggesting that risk-reduction counseling and educational efforts should be focused on the youngest service members who receive LARC.