Our goal was to develop a patient-centered text-message intervention for adolescent females in an urban safety-net health system. We conducted interviews with adolescent females to explore sexual health knowledge and inform the development of a text-messaging intervention. Focused group discussions (FGDs) verified or challenged interview themes and elicited preferences for intervention design. Forty-two females participated, including 15 interviewees and 27 FGD participants. Over half (67%) were Hispanic/Latina, 19% Black, 10% White and 5% Asian. The average age was 16 (±1.5) and 55% reported ever having sex. Participants felt susceptible to and were more concerned with preventing unintended pregnancies than sexually transmitted infections, and described more barriers to condom use than other contraceptive methods. Their input informed the development of a text-messaging intervention, which is described. This study supports the acceptability of a patient-centered texting intervention for promoting and normalizing healthy sexual behaviors among adolescent females in an urban safety-net setting.