In management, restoration, and policy contexts, the notion of resilience can be confusing. Systematic development of conceptual models of ecological state change (state transition models; STMs) can help overcome semantic confusion and promote a mechanistic understanding of resilience. Drawing on examples from rangelands, I describe basic state change concepts (equilibrium, nonequilibrium, and regime shifts) and how they are matched (or mismatched) to specific ecosystems via historical, comparative, experimental, and monitoring evidence. A key issue is to distinguish regime shifts from other forms of state change. STMs should distinguish strategies used to prevent regime shifts vs. the restoration and management of historical/hybrid/novel ecosystems following a regime shift. Important challenges in the development of STMs include 1) defining reference conditions, 2) considering climate change, and 3) information delivery to users.  Paper No. SY48.2.