Background: This article describes a school-wide sexually transmitted infection (STI) screening to identify adolescent high-risk sexual behaviors, STI history/incidence, and presence of chlamydia and gonorrhea, and examines relationships between high-risk behaviors and screening positive for chlamydia and gonorrhea in an alternative high school setting. Methods: School-wide chlamydia and gonorrhea education and screening was provided to 869 adolescents; 226 males and 282 females 14-20 years (mean age = 17.07) consented to urine screening. Relationships were examined between screening positive, history of STIs, and high-risk sexual behaviors. Results: A majority (69%) of the adolescents consented to screening: 17.76% (92) had a history of STI; 8.83% (46) tested positive at screening. More females than males tested positive (p = 0.001). Signi?cant relationships existed between history of STIs and greater than or equal to 4 sexual partners (p = 0.0022), no condom use (p = 0.06), and sexual intercourse in last 3 months (p = 0.03). Conclusions: School-Based Health Center (SBHC) screening was well accepted by students and staff. Sexually transmitted infection history was correlated with all identi?ed high-risk sexual behaviors supporting the need for in-depth assessment, counseling, and testing of adolescents wherever they present for care. This study also provides an example of the role SBHCs can play in the national strategy to control chlamydia and gonorrhea in adolescents. (Contains 3 tables.)