This manuscript describes the randomized clinical trial titled Stage-Matched Intervention to Increase Dual Method Use or Project PROTECT. Project PROTECT compared two approaches to promote the use of dual methods of contraception among high-risk women. The intervention arm received tailored individualized feedback based on the Transtheoretical Model of Behavior Change using a computer-based multimedia program. The control arm received general information on contraception. The primary outcomes of this trial were 1) self-reported use of dual methods of contraception and 2) the biological outcomes of an unintended pregnancy or an incident or recurrent sexually transmitted disease. In this report, we describe the significance and background of the problem, the specific aims of the study, study organization, patient selection, randomization, outcome variables, data collection, procedures used for follow-up and testing, primary and secondary outcomes, and statistical analyses. We also describe participant characteristics and procedures used to assure patient safety and trial monitoring.