Global change has led to an increasing demand for concepts connecting ecological and societal targets for environmental quality. Concepts such as ecosystem functioning or resilience are ciphers for such targets. Practitioners are, however, often left with vague recommendations to maintain the “functioning of ecosystems”, or the “resilience of land-use systems”. The precise meaning of these concepts often remains elusive. As a tool for operationalizing these concepts, the approach of systems-identity has been suggested. Determining the (self-)identity of an ecosystem means to formulate the essential characteristics of an ecological system in an unambiguous way – as a baseline to assess changes and the question if the system is still the same. Several such approaches have been formulated, focussing, for example, on the resilience of social-ecological systems (Cumming et al. 2005) or the self-identity of ecological systems (Jax et al. 1998). The identity-methodology is considered a tool for explicating and communicating concepts such as “ecosystem functioning” or “resilience” and for identifying targets of conservation or resource management. This workshop will discuss the methodology of self-identity within the environmental sciences. We will address the following questions: (1) (How) can the identity-method be applied to empirical systems? (2) Does it help to explicate sustainability-related concepts, such as “functioning” or “resilience”? (3) Can identity foster communication among scientists and between theory and practice? and (4) What differences exist between applying the method to ecological, social, or social-ecological systems? One outcome of the workshop might be the preparation of a corporate publication and/or a symposium.