Sexually transmitted infections (STIs) are an ongoing public health issue in adolescents. the Centers for Disease Control and Prevention and American Academy of Pediatrics have and continue to recommend STI screening in at-risk adolescents, however screening and testing continues to lag behind the need. We previously designed and implemented an electronic risk assessment tool to support STI testing in our pediatric emergency department. Pediatric primary care clinics may be better positioned for STI risk assessments, as they can offer greater privacy and confidentiality, a lower stress environment, and greater opportunity for longitudinal care. STI risk assessment and testing continues to be a challenge in this setting. The goal of this work was to evaluate the usability of our electronic tool to support adaptation and implementation in pediatric primary care practices. We conducted qualitative interviews of pediatricians, clinic staff, and adolescents from 4 pediatric practices as part of a study whose goal is to ultimately implement STI screening in pediatric primary care. The goal of the interviews were (1) to understand contextual factors related to STI screening in primary care, which we have reported previously, and (2) to obtain feedback on our electronic platform, the questionnaire content, and their perspective on implementing it in primary care settings, which we report here. We received quantitative feedback using the System Usability Scale (SUS). The SUS is a validated, reliable tool to measure the usability of hardware, software, websites, and applications. SUS scores range from a score of 0 to 100, with a score of 68 or higher indicating above average usability. We additionally obtained qualitative feedback via interviews and used inductive analysis to identify common themes. We recruited 14 physicians, 9 clinic staff, and 12 adolescents. Participants rated the tool highly using the SUS, with a median score of 92.5 (threshold for average usability is 68) and an interquartile range of 82.5 to 100. Thematically, all participants perceived a need for such a screening program and indicated the format would encourage more honest responses on the topic adolescents. We used these results to modify the questionnaire prior to implementing it into participating practices. We demonstrated that our electronic STI risk assessment tool had a high level of usability and could be adapted for use in pediatric primary care.