Background: As hospital crowding has increased, more patients have ended up boarding in the emergency department (ED) awaiting their inpatient beds. To the best of our knowledge, no study has compared the quality of care of boarded and nonboarded patients. Objectives: This study sought to examine whether being a boarded patient and boarding longer were associated with more delays, medication errors, and adverse events among ED patients admitted with chest pain, pneumonia, or cellulitis. Methods: This study was a retrospective cohort design in which data collection was accomplished via medical record review from two urban teaching hospitals. Patients admitted with chest pain, pneumonia, or cellulitis between August 2004 and January 2005 were eligible for inclusion. Our outcomes measures were: 1) delays in administration of home medications, cardiac enzyme tests, partial thromboplastin time (PTT), and antibiotics; 2) medication errors; and 3) adverse events or near misses. Primary independent variables were boarded status, boarding time, and boarded time interval. Multiple logistic regression models controlling for patient, ED, and hospital characteristics were used. Results: A total of 1,431 patient charts were included: 811 with chest pain, 387 with pneumonia, and 233 with cellulitis. Boarding time was associated with an increased odds of home medication delays (adjusted odds ratio [AOR] = 1.07, 95% confidence interval [CI] = 1.05 to 1.10), as were boarded time intervals of 12, 18, and 24 hours. Boarding time also was associated with lower odds of having a late cardiac enzyme test (AOR = 0.93, 95% CI = 0.88 to 0.97). Conclusions: Boarding was associated with home medication delays, but fewer cardiac enzyme test delays. Boarding was not associated with delayed PTT checks, antibiotic administration, medication errors, or adverse events/near misses. These findings likely reflect the inherent resources of the ED and the inpatient units.