This study tested the association between hospital structural characteristics-teaching status, bedsize, and nurse staffing-and potentially preventable adverse events. The authors calculated 14 Agency for Healthcare Research and Quality Patient Safety Indicators (PSIs) and a PSI composite, using discharge databases from VA and nonfederal hospitals. This study compared the likelihood of PSI events in hospitals, controlling for structural and other characteristics, including patients' case-mix. Additional controls were employed to account for differences in VA versus nonfederal patients and data. The study found some associations, most notably a positive (unfavorable) association between status as a major teaching hospital and six PSIs. However, for most PSIs, the authors found no association between the structural characteristics tested and likelihood of PSI events. The study's findings extend previous research showing a lack of consistent relationship between structural characteristics and patient safety. However, the results also suggest continued need for examination of the relationship between teaching status and potentially preventable adverse events.