One of the most interesting and potentially useful outcomes of recent collaboration between natural and social scientists concerned with the sustainability of jointly determined ecological-economic systems is the application of the ecological concept of resilience. In its broadest sense, resilience is a measure of the ability of a system to withstand stresses and shocks – its ability to persist in an uncertain world. For many policy-makers, however, the concern that desirable states or processes may not be ‘sustainable’ is balanced by the concern that individuals and societies may get ‘locked-in’ to undesirable states or processes. Many low-income countries, for example, are thought to have been caught in poverty traps, and poverty traps have since been seen as a major cause of environmental degradation (Dasgupta, 1993). Other examples of ‘lock-in’ include our dependence on hydrocarbon-based technologies, or the institutional and cultural rigidities that stand in the way of change (Hanna, Folke, and Mäler, 1996). Such states or processes are too persistent.