Political ecology emerged in the 1980s as an interdisciplinary field that analyzed environmental problems using the concepts and methods of political economy. A central premise of the field is that ecological change cannot be understood without consideration of the political and economic structures and institutions within which it is embedded. The nature-society dialectic is the fundamental focus of analysis. Marxian political economy provided the initial primary theoretical influence, while the development of post-structural social theory and nonequilibrium ecology infused new ideas and concepts in subsequent years. A range of methodological approaches characterize political ecology research, including multiscalar analysis, political-economic analysis, historical analysis, ethnography, discourse analysis, and ecological field studies. Political ecology's approach to nature-society relations has explicitly linked capitalist development with ecological change across multiple temporal and spatial scales. The field has been an important source of critical analyses of the social and ecological effects of economic development and conservation initiatives, focusing particularly on the material and discursive aspects of property rights. Recent trends and future directions for research include an expanding urban political ecology theme, critical responses to environmental security theory, an engagement with the philosophies of ethics, and a focus on environment and identity.