This commentary provides an overview of current patient safety knowledge, how it applies to hospitalized patients, and the issues facing pediatric populations in particular. The author begins by discussing the roles cognition and complexity play in medical error and provides current definitions of important safety nomenclature. He builds on the discussion by examining different approaches to evaluating safety. Current understanding of hospital-based rates of adverse events is provided along with proposed prevention strategies. The author shares the immediate challenges for our health care system and advocates for better translation of improvements into practice.