Surveillance, a method used in epidemiology to study the incidence, distribution and control of disease, is an important means of gathering and analyzing information that can be used as needed to effect change. Surveillance has been an important component of the Blueprint for Patient Safety at the Hospital for Sick Children to identify potential and existing vulnerabilities and failures and put measures in place to avoid and mitigate any harm. Reviewing internal reports and actively seeking vulnerabilities has allowed us to make important changes to improve patient safety at the hospital. In this article, we review four internal surveillance strategies that have been particularly successful in driving change - safety reports, morbidity and mortality reviews, patient safety walkarounds and shoe leather infection control rounds - and discuss the successes and challenges we have experienced.