This document discusses complexity science and complex adaptive systems (CAS). It defines complexity science as emerging from simple rules and focusing on relationships among variables. CAS are made up of agents that interact according to patterns and simple rules, which can result in complex and unpredictable behaviors. Healthcare organizations are examples of CAS, as they consist of interconnected systems that are dynamic and adaptive. Viewing healthcare through the lens of complexity science and CAS fits with nursing's holistic approach and supports flexibility, creativity and decentralized leadership in organizations.