Background: Literature suggests that adolescents may not accurately report sexual activity to their providers, impeding risk-based screening efforts for gonorrhea and chlamydia (GC/CT). We assessed the effect of a clinic-based universal GC/CT screening initiative on GC/CT screening frequency and detection of GC/CT infections among adolescents (boys and girls ≥13 years) and the association between positive GC/CT and documented sexual activity. Methods:We conducted a pre-post analysis of a primary care clinic affiliated with an academic institution. The electronic medical record was queried to extract all adolescent well and acute encounters for the 12 months preimplementation and postimplementation of universal GC/CT screening in January 2015.Results: Eight hundred fifty-six encounters from 752 unique adolescents were included. Screening increased postimplementation (23.3% vs 61.4%, P < 0.001) of universal screening. Although there were similar rates of documented sexual activity preimplementation and postimplementation (14.6% vs 16.0%), a larger proportion of unknown sexual activity was documented (10.5% vs 23.7%, P < 0.001). Provider-level factors were the most frequent reasons for not screening. The absolute number of GC/CT cases increased, although the proportion of cases out of all eligible adolescents remained similar as more testing was completed (chlamydia, 5 of 752 vs 12 of 752; P = 0.09; gonorrhea, 0 of 752 vs 1 of 752; P = 0.32). Nearly half of positive chlamydia infections postimplementation appeared in adolescents who reported no sexual activity.