We describe lessons for safety from a synthesis of seven studies of teamwork, leadership and team training across a healthcare region. Two studies identified successes and challenges in a unit with embedded team training: a staff survey demonstrated a positive culture but a perceived need for greater senior presence; training improved actual emergency care, but wide variation in team performance remained. Analysis of multicenter simulation records showed that variation in patient safety and team efficiency correlated with their teamwork but not individual knowledge, skills or attitudes. Safe teams tended to declare the emergency earlier, hand over in a more structured way, and use closed-loop communication. Focused and directed communication was also associated with better patient-actor perception of care. Focus groups corroborated these findings, proposed that the capability and experience of the leader is more important than seniority, and identified teamwork and leadership issues that require further research.