Emergency department crowding and the consequential delays in patient care have been long-standing problems, but as recently as 10 years ago, there was little evidence of their impact on patients. Since that time, there has been a substantial and convincing number of studies published indicating that crowding and delays compromise access to emergency care, quality of emergency care delivered, and patient outcomes, including survival. Further, there is evidence that these threats to patient well-being are more prevalent among vulnerable populations, specifically racial and ethnic minorities. This chapter presents results of recent studies that investigated the relationship between emergency department delays and crowding and patient outcomes. It concludes with a discussion about strategies to reduce crowding and delays.