This paper provides an overview of the concepts of vulnerability, adaptation and adaptive capacity, with reference to related concepts like resilience, risk, sensitivity, hazard, exposure, stability, coping and adaptability, especially as they have been used in the context of climate change. The paper reviews common interpretations and applications of the terms, and develops a general conceptual model of vulnerability as it relates to human societies or communities. The paper also provides a critique of analytical approaches and methods to assess vulnerability and to identify opportunities to enhance adaptive capacity and to provide information directly applicable to the development of adaptation strategies. These methods are described to show how ethnographic principles and procedures provide insights that can be systematically integrated with institutional analyses and modeling of climatic, hydrologic and ecologic systems.