This course will examine some of the practices to renew or restore ecosystems and habitats that were damaged or destroyed by human intervention. Restoration projects purpose is to change disturbed areas into functioning ecosystems, able to provide ecosystem services or function as a natural habitat again. A great example is the watershed protection program of the rivers providing water to New York City. The project initiated in the early 1990's, as a result of critical issues with the city water quality. A water treatment plant would involve 6 billion USD for construction, and 300 million USD for annual maintenance after that. Restoring the wetland ecosystems able to filter the water and eliminate toxic chemicals had a cost of 1 billion USD over 10 years. The course will analyze the biological and physical aspects of restoration ecology. It also will emphasize the role played by society in a successful restoration project. Guidance for the design of a natural ecosystem restoration project will be provided. 23 different case studies are presented in the course, and will provide practical tools and techniques already tested on the field of restoration ecology projects.