Objectives: Despite effective approaches for managing chlamydial infection, asymptomatic disease remains highly prevalent. We linked administrative data with physician data from the American Medical Association physician survey to identify characteristics of primary care offices associated with best chlamydia screening practices. Study: Criteria from the National Committee for Quality Assurance provided chlamydia screening rates. We defined top-performing offices as those with rates in the top decile among 978 primary care offices from 26 states. Results: Offices screened an average of 16.2% of at-risk, young women, but top-performing offices screened 42.2%. Top-performing offices on average had more black physicians (12.5%, 5.1%, P = 0.001) and were more often located in zip code areas with median income less than $30,000 (22.6%, 5.5%, P = 0.001). Conclusions: Although chlamydia screening rates are alarmingly low overall, there is substantial variation across offices. Understanding predictors of better office performance may lead to effective interventions to promote screening. Copyright © 2005, American Sexually Transmitted Diseases Association All rights reserved.