Medical errors are common and can lead to patient harm and death. Most research on errors has focused on inpatient care, yet errors are at least as common in the outpatient setting and likely are underreported. Common types of errors in the outpatient setting are diagnostic, drug, and testing errors. The most effective specific interventions for reducing errors in the outpatient setting remain unknown. Considering the current lack of data, the authors recommend a quality improvement approach to understanding local factors in patient safety. Appropriate education and training of all staff members in their roles in patient safety is an important aspect of any program to reduce errors, though these measures rarely are sufficient on their own. Creation of a culture of safety, use of adequate systems and policies for reporting and identifying errors, and use of technologies to prevent errors also are important.