Objective The objective of the study was to evaluate attitudes and practice patterns of obstetricians related to screening for group B streptococcal colonization and providing intrapartum antibiotic prophylaxis against early-onset neonatal infections with group B streptococcus. Study Design We mailed a survey to 546 members of the American College of Obstetricians and Gynecologists, including members of the Collaborative Ambulatory Research Network and non-Collaborative Ambulatory Research Network members. Stratified random selection was used to generate samples from both of these groups. Results The survey response rate was 60% for Collaborative Ambulatory Research Network members and 42% for non-Collaborative Ambulatory Research Network members. Of the 206 respondents who reported providing prenatal care, 97% collect screening samples at 35-37 weeks' gestational age. Anatomic sites used to collect samples were more variable: 62% include lower vagina and rectum, 26% include lower vagina and perianal skin but not rectum, and 5% include neither the perianal skin nor the rectum. First-line agents for intrapartum antibiotic prophylaxis were penicillin (71%), ampicillin (27%), and cefazolin (2%). For patients reporting a nonanaphylactic penicillin allergy, drugs used for intrapartum antibiotic prophylaxis were more varied: cefazolin (51%), clindamycin (36%), vancomycin (8%), and erythromycin (5%). For patients undergoing a labor induction starting with a cervical ripening agent, less than 40% typically give the first dose of intrapartum antibiotic prophylaxis before or at the time of cervical ripening agent administration, and 15% wait until the patient reaches the active phase of labor. Conclusion Gaps in knowledge and reported practice related to the prevention of early-onset neonatal group B streptococcus infections were similar to gaps in implementation of guidelines demonstrated in past studies. New approaches to improve implementation are warranted.