The American Academy of Pediatrics (AAP) defines standard guidelines for infant positioning and sleep environment to reduce the rate of sudden infant death syndrome (SIDS), but recent data on nurses' knowledge and adherence to these guidelines in hospital settings are limited. An observational, quantitative, and descriptive study was conducted on well-baby postpartum nurseries at two urban Washington, DC, hospitals. Sixty-six direct observations of infant position and crib environment were conducted, and a 17-question survey was administered to determine nurses' knowledge and practice regarding AAP SIDS prevention guidelines. Of observed sleeping conditions, 69.7% failed the guidelines for infant positioning, crib environment, or both, despite nurses' reporting knowledge of the AAP guidelines. Further research is needed to determine if the study's findings are consistent with hospitals elsewhere, and to better understand the disconnect between nurses' knowledge and behavior regarding SIDS prevention guidelines.