This article discusses aspects of ambulatory care that increase the difficulty of practicing infection control in this setting or that require infection control staff to use different methods than they would use in the inpatient setting. The article reviews basic infection control precautions that apply to the outpatient setting in general and specific precautions that apply to dialysis centers and physical therapy programs. The article also describes outbreaks that have occurred in the outpatient setting, defines the deficiencies in infection control practice that caused the outbreaks, and discusses methods to prevent transmission of pathogens in the outpatient setting.